OBJECTIVE To determine the effect of non-closure of the visceral and parietal peritoneum during cesarean section on short-term postoperative morbidity. METHODS A prospective randomized trial was conducted of 533 women undergoing primary cesarean section; 277 were randomized to closure and 256 to non-closure of the peritoneum. Perioperative outcome measures, such as analgesia dosage and morbidly measures were compared. RESULTS There was no significant difference between the non-closure and closure groups in the mean number of narcotic analgesia doses (1.09 +/- 1.2 vs 1.05 +/- 1.0, P = 0.63; respectively), mean number of non-narcotic analgesia doses (4.69 +/- 2.7 vs 4.65 +/- 2.8, P = 0.89; respectively), number of women with postoperative fever >38 degrees C (18 vs 14, P = 0.37; respectively), number of women with wound infection (29 vs 35, P = 0.54; respectively) and mean number of hospitalization days (4.16 +/- 0.91 vs 4.14 +/- 0.71, P = 0.78; respectively). CONCLUSIONS Closure or non-closure of the peritoneum at cesarean sections has no significant impact on postoperative analgesic usage and short-term morbidity.