Controversy remains whether patients with body mass index (BMI) > or =50 kg/m2 experience more complications after laparoscopic Roux-en-y gastric bypass (LRYGB) than those with a lower BMI. Whether BMI > or =50 kg/m2 is associated with specific complications remains unknown. Charts of 152 patients who underwent LRYGB were reviewed. Logistic regression was used to determine whether high BMI is associated with minor or major complications. Overall, there was a trend that major complications occurred more frequently in patients with BMI > or =50 compared with BMI < 50, (30.4% vs. 19.8%, P = 0.138). Major bleeding complications occurred in 16.1 per cent of high BMI patients as compared with 5.2 per cent with lower BMI (P = 0.025). Multivariate regression found that BMI > or =50 was associated with higher odds of a major technical complication (OR = 2.73, P = 0.04), particularly for bleeding complications (odds ratio [OR] = 5.59, P = 0.01). Male gender was also associated with higher odds of a major technical complication (OR = 3.43, P = 0.04). These results suggest that high BMI patients may be better candidates for other types of weight loss surgery, such as staged procedures, and that surgeons early in their career should operate on patients with lower BMI.