The orthotopic neobladder has become the preferred method of handling the urinary tract after removal of the bladder in men and women. However, an improved quality of life compared to urinary diversion fails to be realized when voiding dysfunction arises. These difficulties with urination range from retention to incontinence. Voiding dysfunction following neobladder construction that persists beyond 6-12 months warrants fluoro-urodynamic evaluation to determine the cause and plan therapy. Although colonic, ileocolonic, gastric, and ileal neobladders have all been deemed acceptable, the S or W-configured, spheroidal shaped neobladders created from ileum are the most popular. Voiding pressures and micturition patterns depend on the type, length, and configuration of bowel segment harvested. These variables also determine the risk of voiding dysfunction, along with the choice of surgical technique, and the age and sex of the patient. Urinary retention is more common in women, especially after urethral nerve sparing. Obstruction is often due to inferior displacement of the bladder neck, which can angulate the urethra. Daytime stress incontinence arises from reduced urethral outlet resistance accentuated by low neobladder capacity, reduced compliance, or elevated neobladder pressures. Night-time incontinence develops as a consequence of absent sensation that permits excessive nocturnal volumes to overcome the impaired continence mechanisms of the bladder outlet. This situation is exacerbated by the loss of physiological storage reflexes. Therapy for retention rests primarily with intermittent self-catheterization. Stress urinary incontinence can be treated with periurethral bulking agents or an artificial urethral sphincter. Nocturnal enuresis is often effectively managed by the use of an alarm clock to awaken the patient several times per night. Knowledge of the pathogenesis and identification of risk factors implies that prevention through proper design of the neobladder, meticulous surgical technique, and patient selection is paramount.