Jejunal diverticular (JD) perforation is an uncommon cause of acute abdominal pain in the elderly. From 1971 to 1994 we treated 13 such patients, 9 men and 4 women, with a mean age of 68 years. All patients experienced sudden onset of abdominal pain, nausea and vomiting, and leukocytosis (range of white blood cell counts, 14,000-21,000). On physical examination, three patients had localized peritonitis, were thought to have appendicitis, and underwent immediate laparotomy and segmental jejunal resection for perforated JD. The remaining 10 patients had abdominal tenderness without peritoneal signs. They were hospitalized and managed expectantly. All experienced worsening signs and symptoms and underwent exploratory laparotomy and resection of the involved jejunal segment 13 hours to 8 days after admission. Although 6 of 13 patients had had JD documented previously, in only 2 patients was perforated JD diagnosed preoperatively. In 8 of 13 patients peritoneal contamination was minimal and was contained within the leaves of the mesentery. Soilage was severe with abscess formation in 5 patients. The longer the delay in operative intervention, the greater the peritoneal soilage. The 3 patients undergoing immediate surgery had minimal contamination. Of the 10 patients initially observed, the mean interval before operation was 74 hours in the 5 patients with severe soilage versus 21 hours in those with minimal contamination. The postoperative course was uneventful in 11 patients. Two patients died. Surgical consultation was delayed (8 days, 12 days) in both patients, who had severe peritoneal contamination and died of sepsis. In conclusion, JD perforation is an uncommon and frequently overlooked cause of acute abdominal pain in elderly patients. Timely operative intervention and resection of the involved jejunum are the keys to a successful outcome. Because the presentation and physical findings of perforated JD can be highly variable, a history of preexisting JD should arouse suspicion for JD perforation as the etiology of acute abdominal pain in the elderly.