OBJECTIVE: The aim of this study was to compare open and laparoscopic sigmoid resection for diverticulitis with the patient and the nursing staff blinded to the surgical approach. METHODS: A total of 113 patients scheduled for an elective sigmoidectomy were randomized to receive either a conventional open (54 patients) or a laparoscopic (59 patients) approach. Postoperatively, an opaque wound dressing was applied and left in place for 4 days, and patients from both groups were managed similarly. The primary endpoints for analysis were (1) postoperative pain; (2) duration of postoperative ileus; and (3) duration of hospital stay (ClinicalTrials.gov, number NCT 00453830). RESULTS: The median duration of procedure was 165 minutes (range, 90-285) in the laparoscopy group and 110 minutes (range, 70-210) in the open group (P < 0.0001). The median delay between surgery and first bowel movement was 76 (range, 31-163) hours in the laparoscopy group versus 105 (range, 53-175) hours in the open group (P < 0.0001). The median score for maximal pain (assessed by a visual analog scale) was 4 (range, 1-10) in the laparoscopy group and 5 (range, 1-10) in the open group (P = 0.05). Finally, the median duration of hospital stay was 5 days (range, 4-69) in the laparoscopy group versus 7 days (range, 5-17) in the open group (P < 0.0001). CONCLUSION: Laparoscopic sigmoid resection is associated with a 30% reduction in duration of postoperative ileus and hospital stay; by comparison, benefits in terms of postoperative pain appear less impressive, when the patient is blinded to the surgical technique.