diff --git a/serial.go b/serial.go
index 2bb7f3e..4420100 100644
--- a/serial.go
+++ b/serial.go
@@ -26,6 +26,9 @@ type Port interface {
 	// Returns the number of bytes written.
 	Write(p []byte) (n int, err error)
 
+	// Wait until all data in the buffer are sent
+	Drain() error
+
 	// ResetInputBuffer Purges port read buffer
 	ResetInputBuffer() error
 
diff --git a/serial_bsd.go b/serial_bsd.go
new file mode 100644
index 0000000..4db5b3d
--- /dev/null
+++ b/serial_bsd.go
@@ -0,0 +1,10 @@
+//go:build darwin || dragonfly || freebsd || netbsd || openbsd
+// +build darwin dragonfly freebsd netbsd openbsd
+
+package serial
+
+import "golang.org/x/sys/unix"
+
+func (port *unixPort) Drain() error {
+	return unix.IoctlSetInt(port.handle, unix.TIOCDRAIN, 0)
+}
diff --git a/serial_linux.go b/serial_linux.go
index 116474d..0ac0f39 100644
--- a/serial_linux.go
+++ b/serial_linux.go
@@ -85,3 +85,13 @@ func setTermSettingsBaudrate(speed int, settings *unix.Termios) (error, bool) {
 	settings.Ospeed = toTermiosSpeedType(baudrate)
 	return nil, false
 }
+
+func (port *unixPort) Drain() error {
+	// simulate drain with change settings with TCSETSW
+	settings, err := port.getTermSettings()
+	if err != nil {
+		return err
+	}
+
+	return unix.IoctlSetTermios(port.handle, unix.TCSETSW, settings)
+}
diff --git a/serial_windows.go b/serial_windows.go
index e393d4e..5c4a576 100644
--- a/serial_windows.go
+++ b/serial_windows.go
@@ -119,6 +119,10 @@ func (port *windowsPort) Write(p []byte) (int, error) {
 	return int(writed), err
 }
 
+func (port *windowsPort) Drain() (err error) {
+	return syscall.FlushFileBuffers(port.handle)
+}
+
 const (
 	purgeRxAbort uint32 = 0x0002
 	purgeRxClear        = 0x0008