There are 2 S-Bahn (commuter train) routes from Munich airport to downtown. One approaches the main Munich station from the east and one from the west. Both go via Karlsplatz and Marienplatz. No subway riding is required, although the S-Bahn ticket is also valid on connecting local transportation (subway, bus, streetcar).
[This message has been edited by Track (edited 02-24-2003).]