The Alpha Magnetic Spectrometer (AMS) is a large acceptance particle detector designed to operate in space in order to measure cosmic ray fluxes for many years. The detector was installed, as part of the scientific program, on board of the International Space Station (ISS) Alpha, flying in low orbit (about 400 km) around the Earth. With this experiment in space it is intended to extend the knowledge of the primary cosmic rays, both in composition and in energy distribution, two characteristics that can be difficult to study with ground-based systems. The data analysis is in progress.