OBJECTIVETo compare an ileocaecal orthotopic bladder, (which has been the standard procedure in Egypt for > 30 years) with the ileal neobladder, as there is no ideal continent orthotopic bladder replacement for patients after cystectomy for bladder cancer. PATIENTS AND METHODSBetween June 1999 and December 2001, 60 patients with invasive bladder cancer were randomized into two groups. Group A comprised 29 patients who had radical cystectomy and reconstruction with an ileal neobladder (median age 50 years, 27 men and two women) and group B included 31 who had an ileocaecal bladder substitution after radical cystectomy (median age 51 years, 28 men and three women). RESULTSThe complication rate after surgery in group A was 17%, with two deaths, one from acute myocardial infarction and the other from haematemesis. In group B, the complication rate was 13%, with two deaths, one from a massive pulmonary embolism and the other from liver cell failure. Daytime continence was achieved in 93% of patients in group A and 90% in group B. The mean ( SD ) postvoid residual urine volume was larger in group A than group B, at 90 (72) vs 12 (20) mL. Acidosis and hyponatraemia were evident in the patients in group A but in none in group B ( P < 0.05). The pelvicalyceal systems were preserved in 85% of patients in group A and 93% in group B during the 2-year follow-up. The mean ( SD ) renal cortical thickness was less in group A than in group B, at 1.8 (0.5) and 1.9 (0.2) cm, respectively. Although the cystometric capacity was greater and the basal pressure less in group A than B, these were not reflected in the degree of diurnal and nocturnal continence or back pressure on the renal units. CONCLUSIONContinence in both pouches was similar but the renal units were preserved better in the ileocaecal than in the ileal neobladder. Residual urine volume was greater in the ileal neobladder, with its potential complications of infection and stone formation, and acidosis was more evident.