To evaluate the safety of long-term administration of sirolimus oral solution for up to 5 additional years, or until the tablet formulation is commercially available (whichever occurs first) in solid organ transplant recipients who are currently receiving sirolimus and who have completed clinical trials with sirolimus (with or without cyclosporine (CsA). To evaluate the pharmacokinetics and safety of long-term administration of sirolimus tablets administered for up to 5 years, or until the tablet formulation is commercially available in solid organ transplant recipients who are currently receiving sirolimus and who have completed clinical trials with sirolimus (with or without CsA) or who are currently enrolled in protocol 0468E1-306-US.