Azathioprine and prednisolone may lead to intolerable long-term side effects in some patients with a renal allograft. We have converted 9 patients with stable grafts but severe side effects from conventional immunosuppression to cyclosporine alone. While the steroid side effects largely resolved and there were no problems with acute rejection associated with conversion, the long-term follow up of these patients has demonstrated a number of problems. The average follow-up period since conversion is now 2 years: 2 patients have died, 2 grafts have been lost, and 1 patient required conversion to azathioprine. Chronic nephrotoxicity, gout, indomethacin-induced acute oliguria, and squamous cell carcinomas were the most troublesome effects seen. The disadvantages of conversion outweigh the advantages in most of the patients that we converted.