A 65-year-old lady presented with a 5-day history of watery diarrhoea and right-sided abdominal pain. Overnight she developed localised peritonitis in the left iliac fossa. An abdominal computed tomography scan revealed free fluid in the abdominal cavity, free air in the retroperitoneum and a small bowel perforation. An emergency laparotomy was carried out which revealed multiple jejunal diverticula, one of which had perforated. Jejunal diverticula have a prevalence of approximately 1% in the general population. Perforation of a jejunal diverticulum is a rare complication. Clinically, this diagnosis may be easily confused with other causes of an acute abdomen. In an elderly person, especially if known to have jejunal diverticulosis, one must have a high index of suspicion for perforation.