The AMS Experiment: Cosmic Ray Measurements in Space Markus Cristinziani - Universite' de Geneve (Markus.Cristinziani@physics.unige.ch) The Alpha Magnetic Spectrometer performed a successful test flight (AMS-01) in June 1998 onboard Space Shuttle Discovery. Data recorded during the 10 days of operation enabled an accurate measurement of primary and second cosmic ray spectra and a search for antimatter. The improved AMS-02 version of the detector is now being constructed and will be installed on the International Space Station for a three years operation. The extended physics program will also include high energy photon measurements. Results and status of AMS will be presented.