INTRODUCTION: Danish guidelines recommend colonoscopy after a case of acute diverticulitis to exclude colorectal cancer (CRC), but evidence in support this practice is limited. A series of studies has reported a low incidence of CRC in patients after they presented with acute diverticulitis, especially in uncomplicated cases. The purpose of this study was to investigate the incidence of CRC after acute diverticulitis detected during colonoscopy. METHODS: All patients seen between January 2010 and November 2017 with a first episode of acute diverticulitis and a subsequent computed tomography and colonoscopy were included. RESULTS: A total of 332 patients were included in the study. The incidence of CRC after a case of uncomplicated acute diverticulitis was 0.8%. The incidence of malignancy was 2.8% in the group of patients with complicated diverticulitis. CONCLUSIONS: This study showed a low risk of CRC after a case of acute diverticulitis and no cases of CRC in patients with uncomplicated diverticulitis without clinical symptoms of CRC. This indicates that revising guidelines in regards to follow-up after diverticulitis may be warranted.none. TRIAL REGISTRATION: not relevant.