To assess the comparative bioavailability of two cyclosporine capsule products with different pharmaceutical formulation an open randomized two-period cross over study was conducted in 24 healthy volunteers. Our results, obtained from cyclosporine HPLC determination onto the whole blood samples collected, show that the test cyclosporine non-SMEDDS formulation was not bioequivalent cyclosporine SMEDDS formulation due to a statistically significantly lower absorption rate. The outcome does not support free and full interchangeability in chronic stable graft recipients of the two products studied, unless validated clinical and laboratory conversion protocols for each kind of organ transplantation are enforce.