The Authors report on a case of a 69 years old woman with an acute peritonitis secondary to a perforated jejunal diverticulum, treated by laparotomy and intestinal resection with end-to-end anastomosis in one layer. The patient was dismissed after seven days, in good general conditions. Jejunal diverticula occur in around 1% of general population. They are usually asymptomatic; sometimes they give origin to dyspepsia or acute manifestations. These are due to complications at the site of the diverticulum like bleeding, occlusion and acute infection with perforation and peritonitis, as occurred in our patient. The main risk in diverticular complications is to prolong the interval between admission of the patient and surgical treatment, favouring the initiation of hypovolemic or septic shock. For these reasons, in most recent years, C.T. and, in case of bleeding, capsule endoscopy, were used in the diagnostic pre-operative work-up. The surgical technique is jejunal resection with direct anastomosis, leaving percutaneous drainage only for patients with an abscess, in poor general conditions for a narcosis.