The prevalence of diverticular disease of the colon is increasing in occidental countries. It would be useful to further decrease the mortality and morbidity after elective sigmoid resection (ESR) for diverticulitis. The aim of this study was to identify modifiable preoperative and intraoperative risk factors for mortality and morbidity after ESR for diverticulitis. A database of 2615 patients who underwent a colon or rectal resection with primary anastomosis between 1985 to 1998 has been constructed from prospective randomized studies published by a French surgical group. Of those patients, 582 had undergone ESR for diverticulitis, and they constitute the population of the present study. A total of 46 potential preoperative and intraoperative risk factors for mortality and morbidity have been studied by univariate and multivariate analysis. The operative mortality for our series was 1.2%, and the overall morbidity was 24.9%. The multivariate analysis revealed two statistically significant independent risk factors of mortality: age >75 (odds-ratio=7.9; 95% confidence interval [CI 1.7-36.6]; p=0.01) and obesity (odds-ratio=5.2; 95% CI [1.1-27.9]; p=0.04). The abdominal morbidity (AM) was 6.5% (38/582). The absence of antimicrobial prophylaxis administration with ceftriaxone was the only significant risk factor for AM in multivariate analysis (p=0.003; odds-ratio=2; 95% CI [1.1-4]). The extraabdominal morbidity (EAM) was 18.4% (107/582). Both chronic pulmonary disease (p=0.008; odds-ratio=2.9; 95% CI [1.4-6]; p=0.008) and cirrhosis (odds-ratio=12; 95% CI [1.2-120]) proved to be significant risk factors for EAM. Weight control prior to surgery, routine administration of prophylactic preoperative antibiotics, and preoperative optimization of the respiratory status of patients with chronic pulmonary disease could decrease the postoperative mortality and morbidity associated with ESR for diverticulitis.