Abstract : The ALICE experiment is one of the four main LHC (Large Hadron Collider) experiments. It is dedicated to the study of a new state of matter : the Quark Gluon Plasma, where quarks and gluons are no longer confined within hadrons. In this document, the physics issues that led to the construction of the ALICE dimuon spectrometer, are described. Next, the R&D on the dimuon spectrometer is presented. The different absorbers are described and experimental tests used to determine their dimensions are presented. The dimuon trigger built using the RPC in streamer mode is then described along with the associated beam and cosmic tests and results. Finally, the tracking system is described in detail and more particularly all its electronics and the first station. The physics constraints on the expected performances of all these systems are clearly defined.