A new technique for fashioning an ileocecal pouch, applicable for both bladder augmentation and continent urinary diversion, is described. A low pressure reservoir is achieved by antimesenteric longitudinal transsection of ileum and cecum and formation of a pouch from the cecum and two ileal loops. The antireflux procedure consists of submucosal tunnel implantation of the ureters into the cecum. Clinical application of the operative technique in 4 cases for bladder augmentation and in another 6 cases for urinary diversion has proven the validity of our functional concept: all patients with Mainz pouch bladder augmentation are completely dry day and night with normal intervals of bladder evacuation. Of the 6 patients with Mainz pouch urinary diversion, 2 rely on a an all alloplastic stomal prosthesis for continence, another 2 have achieved continence with isoperistaltic ileo-ileal invagination, and the remainder are awaiting implantation of a sphincteric device.