Twenty-five patients with bladder exstrophy were treated by implanting the vesical trigone into the sigmoid colon. Twenty-three have been followed for 3 to 19 years, with an average of 10 years. Taking into account the clinical status, renal function, the intravenous urogram, continence and social life, 18 patients were considered to have had an excellent result. There were 2 failures; 1 post-operative death occurred due to ruptured oesophageal varices and 1 patient developed bilateral hydronephrosis which necessitated cutaneous urinary diversion. In 4 cases the results, while satisfactory, were only fair in that 2 developed stones and 2 showed symptomatic electrolyte disturbances requiring treatment. Trigonosigmoidostomy preserves intact the ureterovesical junction which prevents colo-ureteric reflux and this probably accounts for the generally excellent long-term results. We believe the operation is preferable to ureterosigmoidostomy in the management of bladder exstrophy.