The records of 51 patients diagnosed with enterovesical fistulas at Virginia Mason Medical Center from 1974 to 1988 were reviewed. Diverticulitis (41%), Crohn's disease (17%), and colorectal cancer (16%) were the major causes. In 50 of 51 patients, the diagnosis was made on the basis of the clinical history and the urine culture. Radiologic and endoscopic studies failed to identify the fistula in 20%, though all were confirmed at operation or autopsy. In four of eight patients with fistulas secondary to colorectal cancer, malignancy was not diagnosed preoperatively. Operation was performed in 84% of the patients. One-stage resection of the bowel was performed in 66% of patients with the intent of removing the fistula. The complication rate was 8% with no deaths. All multi-stage procedures were performed for fistulas complicated by abscess or bowel obstruction. There were two postoperative deaths in patients with metastatic cancer undergoing palliative diversion. All eight patients treated by diverting colostomy had persistent fistulas and urinary sepsis. All eight patients treated with antibiotics but without operation were free of complications of the fistula until death from other causes. Enterovesical fistula is a clinical diagnosis. Preoperative studies should be used to delineate the bowel disease and search for malignancy rather than to see the fistula, which is clinically apparent. One-stage resection of the involved bowel is the procedure of choice in the absence of abscess or bowel obstruction. When resection is not feasible, medical management with antibiotics is preferable to colostomy.