diff --git a/src/emu/bus/msx_cart/msx_audio.c b/src/emu/bus/msx_cart/msx_audio.c
index 258aeebb703..f515db3828e 100644
--- a/src/emu/bus/msx_cart/msx_audio.c
+++ b/src/emu/bus/msx_cart/msx_audio.c
@@ -32,7 +32,7 @@ The keyboards:
 
 
 TODO:
-- Implement MIDI in/out/through
+- Test MIDI in/out/through
 - Sample RAM
 - Implement NMS-1160 keyboard
 - HX-MU901: ENTER/SELECT keys and multi sensors
@@ -112,6 +112,8 @@ msx_cart_msx_audio_nms1205::msx_cart_msx_audio_nms1205(const machine_config &mco
 	, msx_cart_interface(mconfig, *this)
 	, m_y8950(*this, "y8950")
 	, m_acia6850(*this, "acia6850")
+	, m_mdout(*this, "mdout")
+	, m_mdthru(*this, "mdthru")
 {
 }
 
@@ -128,6 +130,14 @@ static MACHINE_CONFIG_FRAGMENT( msx_audio_nms1205 )
 
 	// There is a 2 MHz crystal on the PCB, the 6850 TX and RX clocks are derived from it
 	MCFG_DEVICE_ADD("acia6850", ACIA6850, 0)
+	MCFG_ACIA6850_TXD_HANDLER(DEVWRITELINE("mdout", midi_port_device, write_txd))
+
+	MCFG_MIDI_PORT_ADD("mdin", midiin_slot, "midiin")
+	MCFG_MIDI_RX_HANDLER(WRITELINE(msx_cart_msx_audio_nms1205, midi_in))
+
+	MCFG_MIDI_PORT_ADD("mdthru", midiout_slot, "midiout")
+
+	MCFG_MIDI_PORT_ADD("mdout", midiout_slot, "midiout")
 MACHINE_CONFIG_END
 
 
@@ -148,12 +158,24 @@ const rom_entry *msx_cart_msx_audio_nms1205::device_rom_region() const
 }
 
 
+WRITE_LINE_MEMBER(msx_cart_msx_audio_nms1205::midi_in)
+{
+	// MIDI in signals is sent to both the 6850 and the MIDI thru output port
+	m_acia6850->write_rxd(state);
+	m_mdthru->write_txd(state);
+}
+
+
 void msx_cart_msx_audio_nms1205::device_start()
 {
 	// Install IO read/write handlers
 	address_space &space = machine().device<cpu_device>("maincpu")->space(AS_IO);
 	space.install_write_handler(0xc0, 0xc1, write8_delegate(FUNC(y8950_device::write), m_y8950.target()));
 	space.install_read_handler(0xc0, 0xc1, read8_delegate(FUNC(y8950_device::read), m_y8950.target()));
+	space.install_write_handler(0x00, 0x00, write8_delegate(FUNC(acia6850_device::control_w), m_acia6850.target()));
+	space.install_write_handler(0x01, 0x01, write8_delegate(FUNC(acia6850_device::data_w), m_acia6850.target()));
+	space.install_read_handler(0x04,0x04, read8_delegate(FUNC(acia6850_device::status_r), m_acia6850.target()));
+	space.install_read_handler(0x05,0x05, read8_delegate(FUNC(acia6850_device::data_r), m_acia6850.target()));
 }
 
 
diff --git a/src/emu/bus/msx_cart/msx_audio.h b/src/emu/bus/msx_cart/msx_audio.h
index d7545af3938..8757c5871a5 100644
--- a/src/emu/bus/msx_cart/msx_audio.h
+++ b/src/emu/bus/msx_cart/msx_audio.h
@@ -4,6 +4,7 @@
 #include "bus/msx_cart/cartridge.h"
 #include "sound/8950intf.h"
 #include "machine/6850acia.h"
+#include "bus/midi/midi.h"
 
 
 extern const device_type MSX_CART_MSX_AUDIO_NMS1205;
@@ -45,9 +46,13 @@ public:
 
 	virtual DECLARE_READ8_MEMBER(read_cart);
 
+	DECLARE_WRITE_LINE_MEMBER(midi_in);
+
 private:
 	required_device<y8950_device> m_y8950;
 	required_device<acia6850_device> m_acia6850;
+	required_device<midi_port_device> m_mdout;
+	required_device<midi_port_device> m_mdthru;
 };