Introduction: Bariatric surgery is effective and safe in treating obese patients with BMI > 40, however, higher preoperative weight could increases morbidity and mortality. Aim: To describe and compare the perioperative and mid term outcomes between hiperobese and morbidly obese patients submitted to gastric bypass. Material and Method: A prospective study of hiperobese patients submitted to gastric bypass over the past 10 years. We analyzed clinical characteristics, perioperative morbimortality and resolution of comorbidities. The results were compared with a group of morbidly obese patients matched by age and sex. Results: 146 hiperobese were operated and compared with 165 morbidly obese patients. 66.8% were female and the average age of the total group was 39.9 +/- 12.4 years, with no significant differences between groups by sex and age. The average BMI was 53 and 44.4 respectively. 21.5% had diabetes mellitus 2,39.5% hypertension, 31% dislipidemia and 8.4% osteoarthritis, with no significant differences between groups except for a higher prevalence of dyslipidemia in the morbidly obeses (p = 0.001). 10.4% had surgical complications during the postoperative period, with no differences between both groups (p = 0.24). One year later all patients had a significant decrease in weight, however, hiperobeses showed a more pronounced decrease (p = 0.001). The fasting glucose, cholesterol and triglycerides levels also showed a significant decrease without reaching differences between the groups. Conclusions: The gastric bypass is effective in achieving weight loss and resolution of comorbidities in morbidly obese as well as hiperobese patients, with no significant differences in surgical complications and mortality.