Most morbidly obese patients complain of abdominal pain after laparoscopic gastric bypass (LGBP) surgery. In this study, the relationship between the prevalence and severity of pain and the drain site was assessed. Fifty morbidly obese patients undergoing LGBP surgery were selected, and a drain was randomly inserted postoperatively to the left 5 mm port in 25 cases and to the right in the other 25. All patients filled out a questionnaire, including a visual analog scale for the quality and quantity of pain, exacerbating and alleviating factors and its relation to patient's positioning, in the first 24 hours, first week, and first month after the operation. In both groups, all patients had abdominal pain 24 hours after the operation. However, in the right-sided drain group, most patients (52%) experienced mild pain, whereas most patients (56%) in the left-sided drain group had severe pain (=0.028). At weeks 1 and 4, there was no significant difference between the two groups in terms of severity of pain (=0.068 and 0.875, respectively, for both times). After the first 24 hours and first week, the mean pain score was significantly lower in the right-sited drain group compared to the left-sited drain group (=0.012 and 0.006). Early abdominal pain after LGBP surgery is significantly reduced in the right-sided drain group.