1. ABSTRACTOn behalf of the German Space Agency, DARA, the Spacelab facility NIZEMI (Slow Rotating Centrifuge Microscope) was developed for IML-2 mission in July 1994. The facility permits the investigation of samples under various levels of acceleration. Primary utilization of the facility during the IML-2 mission is for the investigation of samples in the field of gravitational biology.For observation purposes two optical units, a microscope and a macroscope, and the infrastructure for thermal control of the samples has been installed on a centrifuge turntable. The acceleration can be adjusted at levels between 10-3 g and 1.5 g.The rotating centrifuge itself and several moveable items like fans and stages, which are attached on the centrifuge turntable, may affect the microgravity environment of Spacelab. The equipment accommodated on the centrifuge turntable does not allow a design for a uniform mass distribution. Resulting unbalances must be compensated by suitable balancing weights.The paper describes the design of NIZEMI for low microgravity disturbances. The different mechanisms of NIZEMI are outlined and their impacts on the microgravity environment are analyzed.For verification of the microgravity requirements for NIZEMI micro dynamic measurements have been performed on a special test facility at Dornier. The capabilities of the test facility are described. Test results of NIZEMI are presented.