A woman with acute intermittent porphyria and a man with variegate porphyria developed chronic renal failure in middle age. After periods on haemodialysis, both received successful cadaveric renal transplants. On the basis of animal porphyrinogenicity studies prednisolone and azathioprine were used in preference to cyclosporin as immunosuppressive agents. Neither of the patients showed any evidence of activation of their porphyria during, or following, transplantation. The findings in these two patients and a review of two previous reports indicate that acute porphyria is not a contraindication to renal transplantation.