  We perform a systematic reevaluation of the constraints on the
flavor-changing neutral current (FCNC) parameters in R-parity conserving and
R-parity violating supersymmetric models. As a typical process, we study the
constraints coming from the measurements on the B0-\bar{B0} system on the
supersymmetric $\delta^d_{13}$ parameters, as well as on the products of the
lambda' type R-parity violating couplings. Present data allows us to put
constraints on both the real and the imaginary parts of the relevant
parameters.
