SCH 546738 delays graft rejection and in combination with cyclosporine, permits permanent engraftment in the rat cardiac allograft transplant model. SCH 546738 was administered orally twice daily at 1, 5 and 15 mpk. Cyclosporine was administered daily at 2.5 mpk. In the combination study, 5 mpk SCH 546738 and 2.5 mpk cyclosporine were administered. SCH 546738 significantly increased the mean survival time of the graft at 1 mpk (MST = 11 days; p < 0.05), 5 mpk (MST = 14 days; p < 0.05) and 15 mpk (MST = 14.9 days; p < 0.05) when compared with the vehicle control (MST = 6 days). Graft survival was analyzed using the log-rank test.