Small intestinal perforation is an infrequent but often fatal complication of a variety of disorders. Treatment of 76 adults with nontraumatic perforation occurring during a 21 year period was reviewed. The majority of perforations were due to mechanical causes, malignancy, and Crohn's disease. An abdominal mass (53 percent, p < 0.05) and fever (81 percent, p < 0.01) were most frequently documented in patients with Crohn's disease, whereas a positive result on fecal occult blood testing (77 percent, p < 0.025) was common in those with malignant perforations. Otherwise, clinical and laboratory manifestations, including radiographic evidence of free air, were inconstant. The overall mortality rate was 29 percent, with 65 (86 percent) of the patients undergoing operation. Survival was independent of diagnostic delay (p > 0.10). In general, despite various causes and delays in diagnosis, resection and primary anastomosis remains an effective treatment for perforation of the small bowel.