From 1971 to 1984 renal transplantation was performed in 20 patients with end stage renal disease who presented with an existing form of urinary diversion. These patients were evaluated with a cystometrogram, voiding cystourethrogram and cystoscopy. In some cases bladder function was studied further by cycling through a suprapubically placed catheter. The bladder was considered unstable in 13 patients and undiversion was done at transplantation. The period of prior diversion ranged from 3 to 20 years (mean 12.7 years). There were no surgical complications postoperatively and normal bladder function returned in all patients. Currently, 8 patients have a functioning renal allograft 16 months to 9 years after transplantation (mean 4.2 years). Seven patients were considered to have a nonusable bladder owing to severe neurogenic disease or refractory contracture. In these patients transplantation was done into a pre-fashioned intestinal conduit (5) or cutaneous ureterostomy (2). Currently, 4 patients have a functioning renal allograft 16 months to 6.2 years after transplantation (mean 3.8 years). Transplantation candidates who present with an existing form of urinary diversion should be evaluated carefully, since many will have a usable bladder. Regardless of whether the bladder is usable, transplantation can be performed safely with no increased surgical or immunological risk.