Background: Visceral fat, especially the greater omentum, seems to be an important factor in the development of some metabolic disturbances such as insulin resistance, hyperglycemia, and dyslipidemia. Therefore, we wanted to evaluate the influence of resecting or leaving in situ the greater omentum in a group of patients with morbid obesity. Methods: Seventy patients with morbid obesity were submitted to laparotomic resectional gastric bypass and an omentectomy was randomly performed in some patients. Body mass index (BMI), serum levels of sugar, insulin, total cholesterol, and triglycerides were determined prior to surgery and followed up on for 2 years afterwards. Results: Two years after surgery, no differences were seen in BMI levels in either group. Blood sugar levels, serum insulin, total cholesterol levels, and serum triglycerides had similar values in both groups. Arterial hypertension had similar behavior. Conclusions: Based on these results, omentectomy is not justified as pa