The Man-Tended Free-Flyer (MTFF) of the European Space Agency's COLUMBUS Program is a free flying pressurized laboratory in which payload processes will be performed in an automatic mode, i.e. without presence of man. Payload servicing as well as spacecraft servicing will be conducted by man i.e. when man-tended. The paper describes the effect of the temporary presence of man on the MTFF design concept, the requirements concerning functions, safety and redundancy of the vital spacecraft subsystems and the work environment for the astronauts. A next step is manned activities in space is an extended combined MTFF/HERMES Mission where, in addition to MTFF servicing, payload processing will be conducted in the MTFF, involving the HERMES crew. Man systems aspects of the MTFF for this extended mission will be addressed. In a growth scenario towards European's permanent presence of man in space, the MTFF is intended to represent a building block for an European Station. The effect of the growth requirement for the MTFF of supporting permanent manned operation will be described. The COLUMBUS Program also includes a Pressurized Laboratory Module which will be attached to the US-International Space Station (ISS). Similarities between that Module and the MTFF related to Man Systems aspects will be shown.