  In the context of SUSY grand unification a link is established between the
hadronic and leptonic soft breaking sectors. Such relation is here exploited in
particular for FCNC processes in B physics. It is shown how bounds on leptonic
FCNC involving the third generation translate into constraints on FC B decays.
In the second part of the contribution we show that tests of lepton
universality in K and B decays can represent an interesting handle to obtain
relevant information on the amount of FCNC in the second and third fermion
generation.
