Many patients with failed renal transplants elect to receive continuous ambulatory peritoneal dialysis (CAPD) as their modality of dialysis. For others, cardiovascular considerations or access difficulties make CAPD a necessary option when these patients return to dialysis. It is unclear what effects renal transplantation, chronic immunosuppressive therapy and graft rejection might have on the integrity of the peritoneal membrane. We report on thirteen patients receiving CAPD who had peritoneal equilibration test (PET) studies after a failed renal transplant. Three of these patients had studies done pre and post transplantation. Our solute equilibration studies demonstrated that for 10 patients studied with the older 4.25% technique the mean post transplantation D/P creatinine was 0.688 (SE:0.039) on the border of high and low average, and the mean D/Do glucose was 0.228 (SE:0.024) in the high transporter range. Three patients tested pre and post transplantation (upon their return to CAPD after graft failure) had no change in these values. From the above data, 13 patients with peritoneal equilibration testing post transplantation have well-functioning peritoneal membranes allowing for adequate dialysis and flexibility in dialysis prescription. We conclude that renal transplantation does not adversely affect peritoneal membrane function if these patients return to CAPD after graft failure.