  The effect of loops involving charginos with up-type squarks, and gluinos
with down-type squarks, on the inclusive decay mode $b\rightarrow s\gamma$ is
studied in the context of minimal $N=1$ Supergravity models with a radiatively
broken electroweak symmetry group. It is confirmed that the strong constraints
imposed by the CLEO upper bound $B(b\rightarrow s\gamma)<5.4\times 10^{-4}$ on
two-Higgs doublets models are much weaker in supersymmetric theories due to
partial cancelations from loops involving charginos and up-type squarks. The
dependence of the branching ratio and the supersymmetry masses on the top quark
mass is explored.
