The surgical technique for construction of the Mainz (mixed augmentation ileum and cecum) ileocecal pouch for bladder augmentation or continent urinary diversion focuses on 3 functional features: creation of a low pressure reservoir of adequate capacity from cecum and 2 ileal loops, which are split open longitudinally, antirefluxing ureteral implantation into cecum or ascending colon, achieved by a standard submucosal tunnel technique, and in cases of bladder augmentation continence depends on competence of the bladder neck and urethral closure mechanisms, while in urinary diversion continent closure of the pouch is achieved by isoperistaltic ileoileal intussusception or implantation of an alloplastic stomal prosthesis. Of 11 patients with Mainz pouch bladder augmentation (5 of which were undiversions) 10 are completely dry day and night with normal intervals of bladder evacuation. Two patients with myelomeningocele are on intermittent catheterization for bladder evacuation, while the remainder void spontaneously without significant residual urine. Of 12 patients with Mainz pouch urinary diversion 6 have an ileoileal intussusception valve and are completely continent, as are 3 of 4 with an alloplastic stomal prosthesis. Two patients still are awaiting implantation of a sphinteric prosthesis.