Internal fistulas in diverticular disease are uncommon and have a reputation of being difficult to treat. Eighty four patients treated from 1960 to April 1986, representing 20.4 percent (84 of 412) of the surgically treated diverticular disease patients, were reviewed. Eight patients had multiple fistulas. Sixty-five percent (60 to 92) of fistulas were colovesical, 25 percent (23 of 92) colovaginal, 6.5 percent (6 of 92) coloenteric, and 3 percent (3 of 92) colouterine fistulas. There were 66 percent (35 of 53) males and 34 percent (18 of 53) females with colovesical fistulas only. Hysterectomies had been performed in 50 percent (12 of 24) and 83 percent (19 of 23) of females with colovesical and colovaginal fistulas, respectively. Operative management included: resection anastomosis, resection with anastomosis and diversion, Hartmann procedure, and three-stage procedure. In the latter half of the series there was a significant decrease in staging procedures with no significant statistical difference in complications. There were three deaths (3.5 percent) in the series. Other complications included: wound infection, 21 percent (18 of 84), enterocutaneous fistula, 1 percent (4 of 84), and anastomotic dehiscence, 5 percent (4 of 84). Primary anastomosis can be performed with acceptable morbidity and mortality and today is the procedure of choice, leaving staging procedures to selected patients.