One-stage repair of colovaginal fistula complicating acute diverticulitis. Fourteen patients with colovaginal fistula secondary to sigmoid diverticulitis were seen between 1964 and 1988. Thirteen had undergone prior hysterectomy. Three different operative approaches were used. Three patients were treated with colostomy alone; one died and the fistula persisted in one. Five patients underwent staged procedures. One patient died of complications after the second stage of a planned three-stage procedure. Four patients underwent a two-stage procedure (fistula takedown, colectomy with colostomy and colostomy closure), all with good results. Six patients were treated with one-stage fistula takedown, colectomy and primary anastomosis, without major complication. We advocate this as the procedure of choice and emphasize the following principles of epidemiology and management: 1) colovaginal fistula complicates diverticulitis in elderly women usually following hysterectomy; this association may be a factor in etiology; 2) vaginography is useful in diagnosis; and 3) planned one-stage repair is the best surgical approach. 