Jejunal diverticulum is an uncommon, acquired condition, and the majority of patients are usually asymptomatic. Jejunal diverticula become clinically relevant when complications, such as diverticulitis, intestinal bleeding, obstruction, or perforation occur. A rare case of acute abdomen due to a perforated jejunal diverticulum is presented. The diagnosis was initially suggested by CT and confirmed intraoperatively when a 74-year-old male patient underwent a segmental jejunal resection with primary anastomosis. A review of the literature indicates the rarity of this condition, and therefore the aetiology, pathogenesis, diagnosis, and management are briefly discussed. An early diagnosis, based on ultrasonography and CT, and consequently prompt resection of the jejunum affected are the keys to a successful outcome. Because a longer duration of symptoms before operation correlates with a worse prognosis, the possibility of a clinical diagnosis of perforated jejunal diverticulum should be entertained as part of any evaluation of acute abdomen, especially in the elderly.