OBJECTIVE To assess the surgical technique of Mainz II urinary diversion and to discuss its simplicity, quickness of performance, short postoperative period, few postoperative complications, as well as its effectiveness allowing patients to have a very good quality of life. METHODS Over the last six and a half years, 47 patients aged between 65 and 76 years (mean age 69.9 +/- 2.5 years) underwent radical cystectomy and Mainz II ureterosigmoidostomy for invasive bladder cancer. All patients were followed according to a standard protocol including assessment of continence, renal function and acid-base balance. RESULTS Most of the patients retained normal renal function, complete continence and acid-base balance. There were no perioperative complications. In three patients there was urine leakage. Four patients presented with pyelonephritis and needed hospitalization. Mild hyperchloraemic acidosis was seen in nine patients. Most of them were pleased from their new quality of life. CONCLUSIONS The modified Mainz II ureterosigmoidostomy is a simple, quick, easy and safe procedure to achieve urinary diversion in invasive bladder cancer resulting in a very good quality of life for patients without altering their appearance and making them capable of performing all kinds of work.