The results have been reviewed of 35 renal transplants performed on 31 patients with end stage polycystic renal disease. Patient survival is 81 per cent and 71 per cent of the patients have functioning grafts at an average followup of 3.1 years. The need for pre-transplant nephrectomy was evaluated early in the series and since then the operation has been practiced selectively. Twenty-two patients have received transplants with both polycystic kidneys in situ, while 2 patients have undergone transplantation after unilateral nephrectomy. In the absence of a history of renal infection or significant hematuria it has proved safe and desirable to leave the polycystic kidneys in situ. During the post-transplant period in such cases there has been no difficulty attributed to the in situ polycystic kidneys after more than 450 patient months of immunosuppressive therapy. The size of the polycystic kidneys has not been an indication of nephrectomy in our series and no significant technical difficulties have been encountered with large polycystic kidneys remaining in situ. Hypertension associated with end stage polycystic kidney disease has been controlled easily and has not proved an indication for pre-transplant nephrectomy.