Aim: To identify prognostc factor for postoperative complications in patients who underwent surgery for complicated acute diverticulitis (CAD). Method: From September 2011 to March 2016 we operated 136 patients for CAD. Multivariate analysis with logistic regression was performed for postoperative morbidity and mortality. Results: Mean age was 68 15 years. In 17 cases (12.5%) the disease was localised at right colon. Postoperative morbidity was 53.7%. According Clavien-Dindo classi- fication, 12.5% of patients had grade III-IV complications with mortality at 15.4%. At multivariate analysis, age  80, chronic renal failure and diffuse peritonitis were independent factors for mortality (respectively; OR 2.8, 95% CI 1.00–8.2; P = 0.005, OR 5.4, 95% CI 1.6–18.3; P = 0.007, OR 2.4, 95% CI 1.2–4.9; P = 0.014). For postoperative morbidity, the only independent factor was left side disease (OR 4.2, 95% CI 1.1–16.0; P = 0.033), while chronic renal failure did not reach significance (OR 3.8, 95% CI 0.9–15.9; P = 0.062). Conclusion: Surgery for CAD has high rate of postoperative adverse events. Partic- ular care must be taken in patients’  80 years, with renal impairment and with Hinchey III-IV disease. Right colonic CAD seems to have a milder postoperative course.