diff --git a/cmd/sointu-track/main.go b/cmd/sointu-track/main.go
index 093e107..5924023 100644
--- a/cmd/sointu-track/main.go
+++ b/cmd/sointu-track/main.go
@@ -28,6 +28,14 @@ func (NullContext) BPM() (bpm float64, ok bool) {
 	return 0, false
 }
 
+func (NullContext) Params() (ret tracker.ExtParamArray, ok bool) {
+	return tracker.ExtParamArray{}, false
+}
+
+func (NullContext) SetParams(params tracker.ExtParamArray) bool {
+	return false
+}
+
 var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to `file`")
 var memprofile = flag.String("memprofile", "", "write memory profile to `file`")
 
diff --git a/cmd/sointu-vsti/main.go b/cmd/sointu-vsti/main.go
index 287877e..638e9e4 100644
--- a/cmd/sointu-vsti/main.go
+++ b/cmd/sointu-vsti/main.go
@@ -22,6 +22,7 @@ type VSTIProcessContext struct {
 	events     []vst2.MIDIEvent
 	eventIndex int
 	host       vst2.Host
+	parameters []*vst2.Parameter
 }
 
 func (c *VSTIProcessContext) NextEvent() (event tracker.MIDINoteEvent, ok bool) {
@@ -52,6 +53,28 @@ func (c *VSTIProcessContext) BPM() (bpm float64, ok bool) {
 	return timeInfo.Tempo, true
 }
 
+func (c *VSTIProcessContext) Params() (ret tracker.ExtParamArray, ok bool) {
+	for i, p := range c.parameters {
+		ret[i] = p.Value
+	}
+	return ret, true
+}
+
+func (c *VSTIProcessContext) SetParams(val tracker.ExtParamArray) bool {
+	changed := false
+	for i, p := range c.parameters {
+		if p.Value != val[i] {
+			p.Value = val[i]
+			p.Name = fmt.Sprintf("P%f", val[i])
+			changed = true
+		}
+	}
+	if changed {
+		c.host.UpdateDisplay()
+	}
+	return true
+}
+
 func init() {
 	var (
 		version = int32(100)
@@ -74,7 +97,22 @@ func init() {
 			})
 		}
 		go t.Main()
-		context := VSTIProcessContext{host: h}
+		parameters := make([]*vst2.Parameter, 0, tracker.ExtParamCount)
+		for i := 0; i < tracker.ExtParamCount; i++ {
+			parameters = append(parameters,
+				&vst2.Parameter{
+					Name:         fmt.Sprintf("P%d", i),
+					NotAutomated: true,
+					Unit:         "foobar",
+					GetValueFunc: func(value float32) float32 {
+						return float32(int(value*128 + 1))
+					},
+					GetValueLabelFunc: func(value float32) string {
+						return fmt.Sprintf("%d", int(value))
+					},
+				})
+		}
+		context := VSTIProcessContext{host: h, parameters: parameters}
 		buf := make(sointu.AudioBuffer, 1024)
 		return vst2.Plugin{
 				UniqueID:       PLUGIN_ID,
@@ -85,6 +123,7 @@ func init() {
 				Vendor:         "vsariola/sointu",
 				Category:       vst2.PluginCategorySynth,
 				Flags:          vst2.PluginIsSynth,
+				Parameters:     parameters,
 				ProcessFloatFunc: func(in, out vst2.FloatBuffer) {
 					left := out.Channel(0)
 					right := out.Channel(1)
diff --git a/go.mod b/go.mod
index e9d25e8..e1e887c 100644
--- a/go.mod
+++ b/go.mod
@@ -2,6 +2,8 @@ module github.com/vsariola/sointu
 
 go 1.21
 
+replace pipelined.dev/audio/vst2 => ../vst2
+
 require (
 	gioui.org v0.5.0
 	gioui.org/x v0.5.0
diff --git a/tracker/action.go b/tracker/action.go
index faa6f5b..60a9e1f 100644
--- a/tracker/action.go
+++ b/tracker/action.go
@@ -176,6 +176,7 @@ func (m *Model) Undo() Action {
 			m.undoStack = m.undoStack[:len(m.undoStack)-1]
 			m.prevUndoKind = ""
 			(*Model)(m).send(m.d.Song.Copy())
+			(*Model)(m).send(m.ExtParams())
 		},
 	}
 }
@@ -193,6 +194,7 @@ func (m *Model) Redo() Action {
 			m.redoStack = m.redoStack[:len(m.redoStack)-1]
 			m.prevUndoKind = ""
 			(*Model)(m).send(m.d.Song.Copy())
+			(*Model)(m).send(m.ExtParams())
 		},
 	}
 }
@@ -408,3 +410,30 @@ func (m *Model) completeAction(checkSave bool) {
 		m.dialog = NoDialog
 	}
 }
+
+func (m *Model) SetExtLink(index int) Action {
+	return Action{
+		do: func() {
+			defer m.change("SetExtLink", ExtParamLinkChange, MajorChange)()
+			p, _ := m.Params().SelectedItem().(NamedParameter)
+			for i := range p.m.d.ExtParamLinks {
+				if i == index {
+					continue
+				}
+				if p.m.d.ExtParamLinks[i].UnitID == p.unit.ID && p.m.d.ExtParamLinks[i].ParamName == p.up.Name {
+					p.m.d.ExtParamLinks[i] = ExtParamLink{}
+				}
+			}
+			if index > -1 {
+				p.m.d.ExtParamLinks[index] = ExtParamLink{UnitID: p.unit.ID, ParamName: p.up.Name}
+			}
+		},
+		allowed: func() bool {
+			if index < -1 || index >= len(m.d.ExtParamLinks) {
+				return false
+			}
+			_, ok := m.Params().SelectedItem().(NamedParameter)
+			return ok
+		},
+	}
+}
diff --git a/tracker/gioui/unit_editor.go b/tracker/gioui/unit_editor.go
index 5a551dd..0bbc78d 100644
--- a/tracker/gioui/unit_editor.go
+++ b/tracker/gioui/unit_editor.go
@@ -24,27 +24,41 @@ import (
 )
 
 type UnitEditor struct {
-	sliderList     *DragList
-	searchList     *DragList
-	Parameters     []*ParameterWidget
-	DeleteUnitBtn  *ActionClickable
-	CopyUnitBtn    *TipClickable
-	ClearUnitBtn   *ActionClickable
-	DisableUnitBtn *BoolClickable
-	SelectTypeBtn  *widget.Clickable
-	caser          cases.Caser
+	sliderList       *DragList
+	searchList       *DragList
+	Parameters       []*ParameterWidget
+	DeleteUnitBtn    *ActionClickable
+	CopyUnitBtn      *TipClickable
+	ClearUnitBtn     *ActionClickable
+	DisableUnitBtn   *BoolClickable
+	SelectTypeBtn    *widget.Clickable
+	ExtLinkMenuBtn   *TipClickable
+	ExtLinkMenuItems []MenuItem
+	ExtLinkMenu      Menu
+	caser            cases.Caser
 }
 
 func NewUnitEditor(m *tracker.Model) *UnitEditor {
 	ret := &UnitEditor{
-		DeleteUnitBtn:  NewActionClickable(m.DeleteUnit()),
-		ClearUnitBtn:   NewActionClickable(m.ClearUnit()),
-		DisableUnitBtn: NewBoolClickable(m.UnitDisabled().Bool()),
-		CopyUnitBtn:    new(TipClickable),
-		SelectTypeBtn:  new(widget.Clickable),
-		sliderList:     NewDragList(m.Params().List(), layout.Vertical),
-		searchList:     NewDragList(m.SearchResults().List(), layout.Vertical),
+		DeleteUnitBtn:    NewActionClickable(m.DeleteUnit()),
+		ClearUnitBtn:     NewActionClickable(m.ClearUnit()),
+		DisableUnitBtn:   NewBoolClickable(m.UnitDisabled().Bool()),
+		CopyUnitBtn:      new(TipClickable),
+		SelectTypeBtn:    new(widget.Clickable),
+		sliderList:       NewDragList(m.Params().List(), layout.Vertical),
+		searchList:       NewDragList(m.SearchResults().List(), layout.Vertical),
+		ExtLinkMenuBtn:   new(TipClickable),
+		ExtLinkMenu:      Menu{},
+		ExtLinkMenuItems: []MenuItem{{Text: "None", IconBytes: icons.HardwarePhoneLinkOff, Doer: m.SetExtLink(-1)}},
 	}
+	for i := 0; i < tracker.ExtParamCount; i++ {
+		ret.ExtLinkMenuItems = append(ret.ExtLinkMenuItems, MenuItem{
+			Text:      fmt.Sprintf("P%v", i),
+			IconBytes: icons.HardwarePhoneLink,
+			Doer:      m.SetExtLink(i),
+		})
+	}
+
 	ret.caser = cases.Title(language.English)
 	return ret
 }
@@ -125,6 +139,7 @@ func (pe *UnitEditor) layoutFooter(gtx C, t *Tracker) D {
 	copyUnitBtnStyle := TipIcon(t.Theme, pe.CopyUnitBtn, icons.ContentContentCopy, "Copy unit (Ctrl+C)")
 	deleteUnitBtnStyle := ActionIcon(gtx, t.Theme, pe.DeleteUnitBtn, icons.ActionDelete, "Delete unit (Ctrl+Backspace)")
 	disableUnitBtnStyle := ToggleIcon(gtx, t.Theme, pe.DisableUnitBtn, icons.AVVolumeUp, icons.AVVolumeOff, "Disable unit (Ctrl-D)", "Enable unit (Ctrl-D)")
+	extLinkMenuBtnStyle := TipIcon(t.Theme, pe.ExtLinkMenuBtn, icons.ContentLink, "Link to external parameter")
 	text := t.Units().SelectedType()
 	if text == "" {
 		text = "Choose unit type"
@@ -132,7 +147,21 @@ func (pe *UnitEditor) layoutFooter(gtx C, t *Tracker) D {
 		text = pe.caser.String(text)
 	}
 	hintText := Label(text, white, t.Theme.Shaper)
+	m := PopupMenu(&pe.ExtLinkMenu, t.Theme.Shaper)
+
+	for pe.ExtLinkMenuBtn.Clickable.Clicked(gtx) {
+		pe.ExtLinkMenu.Visible = true
+	}
+
 	return layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
+		layout.Rigid(func(gtx C) D {
+			dims := extLinkMenuBtnStyle.Layout(gtx)
+			op.Offset(image.Pt(0, dims.Size.Y)).Add(gtx.Ops)
+			gtx.Constraints.Max.Y = gtx.Dp(unit.Dp(300))
+			gtx.Constraints.Max.X = gtx.Dp(unit.Dp(180))
+			m.Layout(gtx, pe.ExtLinkMenuItems...)
+			return dims
+		}),
 		layout.Rigid(deleteUnitBtnStyle.Layout),
 		layout.Rigid(copyUnitBtnStyle.Layout),
 		layout.Rigid(disableUnitBtnStyle.Layout),
diff --git a/tracker/model.go b/tracker/model.go
index 44a58aa..2d53f52 100644
--- a/tracker/model.go
+++ b/tracker/model.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math"
 	"os"
 	"path/filepath"
 
@@ -11,6 +12,8 @@ import (
 	"github.com/vsariola/sointu/vm"
 )
 
+const ExtParamCount = 16
+
 // Model implements the mutable state for the tracker program GUI.
 //
 // Go does not have immutable slices, so there's no efficient way to guarantee
@@ -37,6 +40,7 @@ type (
 		RecoveryFilePath        string
 		ChangedSinceRecovery    bool
 		Loop                    Loop
+		ExtParamLinks           [ExtParamCount]ExtParamLink
 	}
 
 	Model struct {
@@ -106,6 +110,16 @@ type (
 		model *Model
 	}
 
+	// ExtParamLink is for linking VST parameters to the patch parameters. There's
+	// fixed number of parameters in the VST plugin and these are linked to
+	// particular parameters of a unit.
+	ExtParamLink struct {
+		UnitID    int
+		ParamName string
+	}
+
+	ExtParamArray [ExtParamCount]float32
+
 	IsPlayingMsg   struct{ bool }
 	StartPlayMsg   struct{ sointu.SongPos }
 	BPMMsg         struct{ int }
@@ -133,6 +147,7 @@ const (
 	BPMChange
 	RowsPerBeatChange
 	LoopChange
+	ExtParamLinkChange
 	SongChange ChangeType = PatchChange | ScoreChange | BPMChange | RowsPerBeatChange
 )
 
@@ -247,6 +262,9 @@ func (m *Model) change(kind string, t ChangeType, severity ChangeSeverity) func(
 			if m.changeType&LoopChange != 0 {
 				m.send(m.d.Loop)
 			}
+			if m.changeType&ExtParamLinkChange != 0 || m.changeType&PatchChange != 0 {
+				m.send(m.ExtParams())
+			}
 			m.undoSkipCounter++
 			var limit int
 			switch m.changeSeverity {
@@ -322,6 +340,7 @@ func (m *Model) UnmarshalRecovery(bytes []byte) {
 	}
 	m.d.ChangedSinceRecovery = false
 	m.send(m.d.Song.Copy())
+	m.send(m.ExtParams())
 	m.send(m.d.Loop)
 	m.updatePatternUseCount()
 }
@@ -355,6 +374,8 @@ func (m *Model) ProcessPlayerMessage(msg PlayerMsg) {
 		m.Alerts().AddAlert(e)
 	case IsPlayingMsg:
 		m.playing = e.bool
+	case ExtParamArray:
+		m.SetExtParams(e)
 	default:
 	}
 }
@@ -389,6 +410,50 @@ func (m *Model) Instrument(index int) sointu.Instrument {
 	return m.d.Song.Patch[index].Copy()
 }
 
+func (m *Model) ExtParams() (ret ExtParamArray) {
+	for i, l := range m.d.ExtParamLinks {
+		instrIndex, unitIndex, err := m.d.Song.Patch.FindUnit(l.UnitID)
+		if err != nil {
+			continue
+		}
+		unit := m.d.Song.Patch[instrIndex].Units[unitIndex]
+		if up, ok := sointu.UnitTypes[unit.Type]; ok {
+			for _, p := range up {
+				if p.Name == l.ParamName && p.CanSet && p.MaxValue > p.MinValue {
+					ret[i] = float32(unit.Parameters[l.ParamName]-p.MinValue) / float32(p.MaxValue-p.MinValue)
+				}
+			}
+		}
+	}
+	return
+}
+
+func (m *Model) SetExtParams(params ExtParamArray) {
+	defer m.change("SetParamValue", PatchChange, MinorChange)()
+	changed := false
+	for i, l := range m.d.ExtParamLinks {
+		instrIndex, unitIndex, err := m.d.Song.Patch.FindUnit(l.UnitID)
+		if err != nil {
+			continue
+		}
+		unit := m.d.Song.Patch[instrIndex].Units[unitIndex]
+		if up, ok := sointu.UnitTypes[unit.Type]; ok {
+			for _, p := range up {
+				if p.Name == l.ParamName && p.CanSet && p.MaxValue > p.MinValue {
+					newVal := int(math.Round(float64(params[i])*float64(p.MaxValue-p.MinValue))) + p.MinValue
+					if unit.Parameters[l.ParamName] != newVal {
+						unit.Parameters[l.ParamName] = newVal
+						changed = true
+					}
+				}
+			}
+		}
+	}
+	if !changed {
+		m.changeCancel = true
+	}
+}
+
 func (d *modelData) Copy() modelData {
 	ret := *d
 	ret.Song = d.Song.Copy()
diff --git a/tracker/model_test.go b/tracker/model_test.go
index 706b05d..69ce4d3 100644
--- a/tracker/model_test.go
+++ b/tracker/model_test.go
@@ -21,6 +21,14 @@ func (NullContext) BPM() (bpm float64, ok bool) {
 	return 0, false
 }
 
+func (NullContext) Params() (params tracker.ExtParamArray, ok bool) {
+	return tracker.ExtParamArray{}, false
+}
+
+func (NullContext) SetParams(params tracker.ExtParamArray) bool {
+	return false
+}
+
 type modelFuzzState struct {
 	model     *tracker.Model
 	clipboard []byte
diff --git a/tracker/player.go b/tracker/player.go
index 52b31da..d4c0d46 100644
--- a/tracker/player.go
+++ b/tracker/player.go
@@ -25,6 +25,7 @@ type (
 		voiceLevels     [vm.MAX_VOICES]float32 // a level that can be used to visualize the volume of each voice
 		voices          [vm.MAX_VOICES]voice
 		loop            Loop
+		extParamValues  ExtParamArray
 
 		recState  recState  // is the recording off; are we waiting for a note; or are we recording
 		recording Recording // the recorded MIDI events and BPM
@@ -39,6 +40,8 @@ type (
 	PlayerProcessContext interface {
 		NextEvent() (event MIDINoteEvent, ok bool)
 		BPM() (bpm float64, ok bool)
+		Params() (params ExtParamArray, ok bool)
+		SetParams(params ExtParamArray) bool
 	}
 
 	// MIDINoteEvent is a MIDI event triggering or releasing a note. In
@@ -225,6 +228,10 @@ func (p *Player) advanceRow() {
 }
 
 func (p *Player) processMessages(context PlayerProcessContext) {
+	if value, ok := context.Params(); ok && value != p.extParamValues {
+		p.extParamValues = value
+		p.send(p.extParamValues)
+	}
 loop:
 	for { // process new message
 		select {
@@ -293,6 +300,8 @@ loop:
 					}
 					p.recState = recStateNone
 				}
+			case ExtParamArray:
+				context.SetParams(m)
 			default:
 				// ignore unknown messages
 			}