  Isospin asymmetry in b -> s gamma transitions provides severe constraints on
new physics parameters, due to the small values of the experimental
measurements. We exploit here this new observable to study different
supersymmetric models. For this purpose, we calculate the isospin symmetry
breaking in the MSSM with minimal flavor violation, considering NLO
contributions. We study three scenarios for supersymmetry breaking, namely
mSUGRA, AMSB and GMSB. In most of the explored regions, we find very
restrictive constraints on the allowed parameters for these models.
