It has recently been suggested that the use of calcium channel-blocking agents may improve the results of renal transplantation either by enhancing the immunosuppressive effects of ciclosporin, or by improving posttransplant acute renal failure. In the present study, unlike others, verapamil was administered to the animals for 10 days posttransplant, alone or in conjunction with ciclosporin and/or solumedrol. In the group in which all three agents were given together, there were minimal changes in plasma urea or creatinine for the 10 days after transplantation. However, survival and the histological appearances of the kidneys at autopsy showed no improvement as compared with those in animals treated with ciclosporin and steroids. There is thus no evidence from this study to suggest that verapamil could advantageously be added to a clinical immunosuppressive regime.