  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.
