SDECAY: a Fortran code for the decays of the supersymmetric particles in the MSSM

We present the Fortran code SDECAY, which calculates the decay widths and branching ratios of all the supersymmetric particles in the Minimal Supersymmetric Standard Model, including higher order effects. Besides the usual two-body decays of fermions and gauginos and the three-body decays of charginos, neutralinos and gluinos, we have also implemented the three-body decays of top squarks, and even the four-body decays of the top squark; the important loop-induced decay modes are also included. The QCD corrections to the two-body decays involving strongly interacting particles and the dominant components of the electroweak corrections to all decay modes are implemented.