The Alpha Magnetic Spectrometer (AMS) is a particle physics experiment
scheduled to be installed on the International Space Station in November 2003. The purpose of this experiment is to provide a high statistics measurement of charged particles and nuclei from 0.1 GeV to 1 TeV, and to provide a sensitive search for cosmic antimatter (antihelium) and dark matter, and to study the properties of cosmic rays. A 10-day test run was carried out on the space shuttle Discovery in June 1998. The physics results of this test run and the progress on the construction of the final detector will be presented.