diff --git a/README.md b/README.md
index d3869a0..94df70e 100644
--- a/README.md
+++ b/README.md
@@ -45,4 +45,5 @@ uv run pre-commit install
 - `flow rebase` — rebase the current branch onto the latest default branch
 - `flow push` — force-push the current branch (refused on the default branch)
 - `flow clean` — delete local branches whose PRs have been merged
+- `flow prune` — prune remote-tracking branches that no longer exist on `origin`
 - `flow dirty` — show the stash list and all local branches
diff --git a/main.go b/main.go
index 4a044f1..3451548 100644
--- a/main.go
+++ b/main.go
@@ -30,7 +30,7 @@ func run(name string, args ...string) {
 func main() {
 	if len(os.Args) < 2 {
 		fmt.Fprintf(os.Stderr, "usage: flow <command> [args]\n")
-		fmt.Fprintf(os.Stderr, "commands: branch, create, view, update, amend, merge, clean, rebase, push, dirty\n")
+		fmt.Fprintf(os.Stderr, "commands: branch, create, view, update, amend, merge, clean, rebase, push, prune, dirty\n")
 		os.Exit(2)
 	}
 
@@ -45,6 +45,8 @@ func main() {
 		cmdUpdate(os.Args[2:])
 	case "amend":
 		cmdAmend(os.Args[2:])
+	case "prune":
+		cmdPrune(os.Args[2:])
 	case "merge":
 		cmdMerge(os.Args[2:])
 	case "clean":
@@ -57,7 +59,7 @@ func main() {
 		cmdDirty(os.Args[2:])
 	default:
 		fmt.Fprintf(os.Stderr, "flow: unknown command %q\n", os.Args[1])
-		fmt.Fprintf(os.Stderr, "commands: branch, create, view, update, amend, merge, clean, rebase, push, dirty\n")
+		fmt.Fprintf(os.Stderr, "commands: branch, create, view, update, amend, merge, clean, rebase, push, prune, dirty\n")
 		os.Exit(2)
 	}
 }
@@ -289,6 +291,15 @@ func cmdPush(args []string) {
 	run("git", "push", "--force")
 }
 
+func cmdPrune(args []string) {
+	if len(args) > 0 {
+		fmt.Fprintf(os.Stderr, "usage: flow prune\n")
+		os.Exit(2)
+	}
+
+	run("git", "remote", "prune", "origin")
+}
+
 func cmdDirty(args []string) {
 	if len(args) > 0 {
 		fmt.Fprintf(os.Stderr, "usage: flow dirty\n")