diff --git a/CHANGELOG.md b/CHANGELOG.md
index 980d1fd..9f44b4d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 ### Added
+- Disable units temporarily. The disabled units are shown in gray and are not
+  compiled into the patch and are considered for all purposes non-existent.
+  Hitting Ctrl-D disables/re-enables the selected unit(s). The yaml file has
+  field `disabled: true` for the unit. ([#116][i116])
 - Passing a file name on command line immediately tries loading that file ([#122][i122])
 - Massive rewrite of the GUI, in particular allowing better copying, pasting and
   scrolling of table-based data (order list and note data).
@@ -125,6 +129,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 [0.3.0]: https://github.com/vsariola/sointu/compare/v0.2.0...v0.3.0
 [0.2.0]: https://github.com/vsariola/sointu/compare/v0.1.0...v0.2.0
 [0.1.0]: https://github.com/vsariola/sointu/compare/4klang-3.11...v0.1.0
+[i116]: https://github.com/vsariola/sointu/issues/116
 [i120]: https://github.com/vsariola/sointu/issues/120
 [i121]: https://github.com/vsariola/sointu/issues/121
 [i122]: https://github.com/vsariola/sointu/issues/122
diff --git a/patch.go b/patch.go
index e6e9046..c2af2b7 100644
--- a/patch.go
+++ b/patch.go
@@ -44,6 +44,10 @@ type (
 		// unit, VarArgs is the delaytimes, in samples, of the different delaylines
 		// in the unit.
 		VarArgs []int `yaml:",flow,omitempty"`
+
+		// Disabled is a flag that can be set to true to disable the unit.
+		// Disabled units are considered to be not present in the patch.
+		Disabled bool `yaml:",omitempty"`
 	}
 
 	// UnitParameter documents one parameter that an unit takes
@@ -220,7 +224,7 @@ func (u *Unit) Copy() Unit {
 	}
 	varArgs := make([]int, len(u.VarArgs))
 	copy(varArgs, u.VarArgs)
-	return Unit{Type: u.Type, Parameters: parameters, VarArgs: varArgs, ID: u.ID}
+	return Unit{Type: u.Type, Parameters: parameters, VarArgs: varArgs, ID: u.ID, Disabled: u.Disabled}
 }
 
 // StackChange returns how this unit will affect the signal stack. "pop" and
@@ -230,6 +234,9 @@ func (u *Unit) Copy() Unit {
 // unit). Effects that just change the topmost signal and will not change the
 // number of signals on the stack and thus return 0.
 func (u *Unit) StackChange() int {
+	if u.Disabled {
+		return 0
+	}
 	switch u.Type {
 	case "addp", "mulp", "pop", "out", "outaux", "aux":
 		return -1 - u.Parameters["stereo"]
@@ -249,6 +256,9 @@ func (u *Unit) StackChange() int {
 // this unit is executed. Used to prevent stack underflow. Units producing
 // signals do not care what is on the stack before and will return 0.
 func (u *Unit) StackNeed() int {
+	if u.Disabled {
+		return 0
+	}
 	switch u.Type {
 	case "", "envelope", "oscillator", "noise", "receive", "loadnote", "loadval", "in":
 		return 0
@@ -350,14 +360,14 @@ func (p Patch) InstrumentForVoice(voice int) (int, error) {
 // given id. Two units should never have the same id, but if they do, then the
 // first match is returned. Id 0 is interpreted as "no id", thus searching for
 // id 0 returns an error. Error is also returned if the searched id is not
-// found.
+// found. FindUnit considers disabled units as non-existent.
 func (p Patch) FindUnit(id int) (instrIndex int, unitIndex int, err error) {
 	if id == 0 {
 		return 0, 0, errors.New("FindUnit called with id 0")
 	}
 	for i, instr := range p {
 		for u, unit := range instr.Units {
-			if unit.ID == id {
+			if unit.ID == id && !unit.Disabled {
 				return i, u, nil
 			}
 		}
diff --git a/tracker/bool.go b/tracker/bool.go
index 9e27df9..bf0936b 100644
--- a/tracker/bool.go
+++ b/tracker/bool.go
@@ -19,6 +19,7 @@ type (
 	CommentExpanded Model
 	NoteTracking    Model
 	UnitSearching   Model
+	UnitDisabled    Model
 )
 
 func (v Bool) Toggle() {
@@ -41,6 +42,7 @@ func (m *Model) Effect() *Effect                   { return (*Effect)(m) }
 func (m *Model) CommentExpanded() *CommentExpanded { return (*CommentExpanded)(m) }
 func (m *Model) NoteTracking() *NoteTracking       { return (*NoteTracking)(m) }
 func (m *Model) UnitSearching() *UnitSearching     { return (*UnitSearching)(m) }
+func (m *Model) UnitDisabled() *UnitDisabled       { return (*UnitDisabled)(m) }
 
 // Panic methods
 
@@ -126,3 +128,36 @@ func (m *UnitSearching) setValue(val bool) {
 	}
 }
 func (m *UnitSearching) Enabled() bool { return true }
+
+// UnitDisabled methods
+
+func (m *UnitDisabled) Bool() Bool { return Bool{m} }
+func (m *UnitDisabled) Value() bool {
+	if m.d.InstrIndex < 0 || m.d.InstrIndex >= len(m.d.Song.Patch) {
+		return false
+	}
+	if m.d.UnitIndex < 0 || m.d.UnitIndex >= len(m.d.Song.Patch[m.d.InstrIndex].Units) {
+		return false
+	}
+	return m.d.Song.Patch[m.d.InstrIndex].Units[m.d.UnitIndex].Disabled
+}
+func (m *UnitDisabled) setValue(val bool) {
+	if m.d.InstrIndex < 0 || m.d.InstrIndex >= len(m.d.Song.Patch) {
+		return
+	}
+	l := ((*Model)(m)).Units().List()
+	a, b := l.listRange()
+	defer (*Model)(m).change("UnitDisabledSet", PatchChange, MajorChange)()
+	for i := a; i <= b; i++ {
+		m.d.Song.Patch[m.d.InstrIndex].Units[i].Disabled = val
+	}
+}
+func (m *UnitDisabled) Enabled() bool {
+	if m.d.InstrIndex < 0 || m.d.InstrIndex >= len(m.d.Song.Patch) {
+		return false
+	}
+	if len(m.d.Song.Patch[m.d.InstrIndex].Units) == 0 {
+		return false
+	}
+	return true
+}
diff --git a/tracker/gioui/instrument_editor.go b/tracker/gioui/instrument_editor.go
index 432a54d..4c314e7 100644
--- a/tracker/gioui/instrument_editor.go
+++ b/tracker/gioui/instrument_editor.go
@@ -7,6 +7,7 @@ import (
 	"strconv"
 	"strings"
 
+	"gioui.org/font"
 	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/layout"
@@ -343,6 +344,7 @@ func (ie *InstrumentEditor) layoutUnitList(gtx C, t *Tracker) D {
 		}
 		u := units[i]
 		var color color.NRGBA = white
+		f := labelDefaultFont
 
 		var stackText string
 		stackText = strconv.FormatInt(int64(u.StackAfter), 10)
@@ -353,6 +355,10 @@ func (ie *InstrumentEditor) layoutUnitList(gtx C, t *Tracker) D {
 			color = warningColor
 			(*tracker.Alerts)(t.Model).AddNamed("InstrumentLeavesSignals", fmt.Sprintf("Instrument leaves %v signal(s) on the stack", u.StackAfter), tracker.Warning)
 		}
+		if u.Disabled {
+			color = disabledTextColor
+			f.Style = font.Italic
+		}
 
 		stackLabel := LabelStyle{Text: stackText, ShadeColor: black, Color: mediumEmphasisTextColor, Font: labelDefaultFont, FontSize: unit.Sp(12), Shaper: t.Theme.Shaper}
 		rightMargin := layout.Inset{Right: unit.Dp(10)}
@@ -381,7 +387,7 @@ func (ie *InstrumentEditor) layoutUnitList(gtx C, t *Tracker) D {
 					editor.Color = color
 					editor.HintColor = instrumentNameHintColor
 					editor.TextSize = unit.Sp(12)
-					editor.Font = labelDefaultFont
+					editor.Font = f
 
 					defer clip.Rect(image.Rect(0, 0, gtx.Constraints.Max.X, gtx.Constraints.Max.Y)).Push(gtx.Ops).Pop()
 					key.InputOp{Tag: &ie.searchEditor, Keys: globalKeys}.Add(gtx.Ops)
@@ -399,7 +405,7 @@ func (ie *InstrumentEditor) layoutUnitList(gtx C, t *Tracker) D {
 					}
 					return ret
 				} else {
-					unitNameLabel := LabelStyle{Text: u.Type, ShadeColor: black, Color: color, Font: labelDefaultFont, FontSize: unit.Sp(12), Shaper: t.Theme.Shaper}
+					unitNameLabel := LabelStyle{Text: u.Type, ShadeColor: black, Color: color, Font: f, FontSize: unit.Sp(12), Shaper: t.Theme.Shaper}
 					if unitNameLabel.Text == "" {
 						unitNameLabel.Text = "---"
 					}
diff --git a/tracker/gioui/keyevent.go b/tracker/gioui/keyevent.go
index d1f2806..9276b1b 100644
--- a/tracker/gioui/keyevent.go
+++ b/tracker/gioui/keyevent.go
@@ -64,6 +64,11 @@ func (t *Tracker) KeyEvent(e key.Event, o *op.Ops) {
 				t.Model.Redo().Do()
 				return
 			}
+		case "D":
+			if e.Modifiers.Contain(key.ModShortcut) {
+				t.Model.UnitDisabled().Bool().Toggle()
+				return
+			}
 		case "N":
 			if e.Modifiers.Contain(key.ModShortcut) {
 				t.NewSong().Do()
diff --git a/tracker/gioui/unit_editor.go b/tracker/gioui/unit_editor.go
index 9a9e8eb..3a86786 100644
--- a/tracker/gioui/unit_editor.go
+++ b/tracker/gioui/unit_editor.go
@@ -21,25 +21,27 @@ import (
 )
 
 type UnitEditor struct {
-	sliderList    *DragList
-	searchList    *DragList
-	Parameters    []*ParameterWidget
-	DeleteUnitBtn *ActionClickable
-	CopyUnitBtn   *TipClickable
-	ClearUnitBtn  *ActionClickable
-	SelectTypeBtn *widget.Clickable
-	tag           bool
-	caser         cases.Caser
+	sliderList     *DragList
+	searchList     *DragList
+	Parameters     []*ParameterWidget
+	DeleteUnitBtn  *ActionClickable
+	CopyUnitBtn    *TipClickable
+	ClearUnitBtn   *ActionClickable
+	DisableUnitBtn *BoolClickable
+	SelectTypeBtn  *widget.Clickable
+	tag            bool
+	caser          cases.Caser
 }
 
 func NewUnitEditor(m *tracker.Model) *UnitEditor {
 	ret := &UnitEditor{
-		DeleteUnitBtn: NewActionClickable(m.DeleteUnit()),
-		ClearUnitBtn:  NewActionClickable(m.ClearUnit()),
-		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),
 	}
 	ret.caser = cases.Title(language.English)
 	return ret
@@ -114,6 +116,7 @@ func (pe *UnitEditor) layoutFooter(gtx C, t *Tracker) D {
 	}
 	copyUnitBtnStyle := TipIcon(t.Theme, pe.CopyUnitBtn, icons.ContentContentCopy, "Copy unit (Ctrl+C)")
 	deleteUnitBtnStyle := ActionIcon(t.Theme, pe.DeleteUnitBtn, icons.ActionDelete, "Delete unit (Ctrl+Backspace)")
+	disableUnitBtnStyle := ToggleIcon(t.Theme, pe.DisableUnitBtn, icons.AVVolumeUp, icons.AVVolumeOff, "Disable unit (Ctrl-D)", "Enable unit (Ctrl-D)")
 	text := t.Units().SelectedType()
 	if text == "" {
 		text = "Choose unit type"
@@ -124,6 +127,7 @@ func (pe *UnitEditor) layoutFooter(gtx C, t *Tracker) D {
 	return layout.Flex{Axis: layout.Horizontal, Alignment: layout.Middle}.Layout(gtx,
 		layout.Rigid(deleteUnitBtnStyle.Layout),
 		layout.Rigid(copyUnitBtnStyle.Layout),
+		layout.Rigid(disableUnitBtnStyle.Layout),
 		layout.Rigid(func(gtx C) D {
 			var dims D
 			if t.Units().SelectedType() != "" {
diff --git a/tracker/list.go b/tracker/list.go
index 8a45dde..644ff21 100644
--- a/tracker/list.go
+++ b/tracker/list.go
@@ -34,6 +34,7 @@ type (
 
 	UnitListItem struct {
 		Type                               string
+		Disabled                           bool
 		StackNeed, StackBefore, StackAfter int
 	}
 
@@ -323,7 +324,13 @@ func (v *Units) Iterate(yield UnitYieldFunc) {
 	stackBefore := 0
 	for _, unit := range v.d.Song.Patch[v.d.InstrIndex].Units {
 		stackAfter := stackBefore + unit.StackChange()
-		if !yield(UnitListItem{unit.Type, unit.StackNeed(), stackBefore, stackAfter}) {
+		if !yield(UnitListItem{
+			Type:        unit.Type,
+			Disabled:    unit.Disabled,
+			StackNeed:   unit.StackNeed(),
+			StackBefore: stackBefore,
+			StackAfter:  stackAfter,
+		}) {
 			break
 		}
 		stackBefore = stackAfter
diff --git a/vm/bytecode.go b/vm/bytecode.go
index de1af53..3fac621 100644
--- a/vm/bytecode.go
+++ b/vm/bytecode.go
@@ -78,7 +78,7 @@ func NewBytecode(patch sointu.Patch, featureSet FeatureSet, bpm int) (*Bytecode,
 			return nil, errors.New("Each instrument must have at least 1 voice")
 		}
 		for unitIndex, unit := range instr.Units {
-			if unit.Type == "" { // empty units are just ignored & skipped
+			if unit.Type == "" || unit.Disabled { // empty units are just ignored & skipped
 				continue
 			}
 			opcode, ok := featureSet.Opcode(unit.Type)
diff --git a/vm/featureset.go b/vm/featureset.go
index c94724b..59cd82c 100644
--- a/vm/featureset.go
+++ b/vm/featureset.go
@@ -118,7 +118,7 @@ func NecessaryFeaturesFor(patch sointu.Patch) NecessaryFeatures {
 	features := NecessaryFeatures{opcodes: map[string]int{}, supportsParamValue: map[paramKey](map[int]bool){}, supportsModulation: map[paramKey]bool{}}
 	for instrIndex, instrument := range patch {
 		for _, unit := range instrument.Units {
-			if unit.Type == "" {
+			if unit.Type == "" || unit.Disabled {
 				continue
 			}
 			if _, ok := features.opcodes[unit.Type]; !ok {