The CMS Si-strip Tracker

The Compact Muon Solenoid (CMS) experiment at LHC features the largest Silicon Strip Tracker (SST) ever build. This device is immersed in a 4T magnetic field and, in conjunction with a Pixel system, it allows the momentum of the charged particles to be measured and the heavy-flavour final states to be tagged despite the hostile radiation environment. The impact of operating conditions and physics requirements on the SST layout and design choices is discussed and the expected performances are reviewed. The SST collaboration is now facing the production of the ~15000 modules and their assembly into the SST substructures. A status is given.