BACKGROUND Jejunal diverticulosis is a rare clinical condition, and the majority of patients are asymptomatic. However, some patients can develop serious complications, including perforation. We report the case of a 74-year-old female patient with a perforated jejunal diverticulum who presented with an 'acute abdomen' and with pneumoperitoneum on X-ray radiography. CASE REPORT A 74-year-old female patient presented to the emergency department with a 24-hour history of acute onset of diffuse abdominal pain associated with nausea and vomiting. Physical examination showed signs of generalized peritonitis. The chest radiograph showed a pneumoperitoneum. An emergency laparotomy was performed, and a perforated jejunal diverticulum was identified. Resection of the involved jejunal segment and a primary jejunal anastomosis were performed. CONCLUSIONS Perforated jejunoileal diverticula should be included in the differential diagnosis for elderly patients who present with an acute abdomen. A delay in the diagnosis can be fatal in this group of patients. Although radiographic signs, such as pneumoperitoneum, are unusual in these cases, this finding should provide a diagnostic clue for the physician.