Background: We compared the early endocrine and metabolic changes associated with sleeve gastrectomy (SG) and gastric bypass (GB) in grade III obese patients. Methods: Fifty morbidly obese patients were randomized into two groups on the basis of their position in the queuegroup A comprised SG and group B was GB. Comparison between the two groups was based on clinical and laboratory variables such as fasting blood glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), glycated hemoglobin (HbA1c), lipids, albumin, and ferritin. Patients were assessed after 7, 14, 30, 60, and 90 days and additional laboratory tests were done on the 90(th) day. Results: The following mean values were recorded for groups A and B, respectively: Age (years), 36.4 and 31.1; weight (kg), 123.2 and 128.3; and body mass index (BMI; kg/m(2)), 45.6 and 47.3. In the first postoperative week, group B showed a greater weight loss (P=0.047) that was not observed after 14, 30, 60, and 90 days (P>0.05). Group A had an average excess weight loss of 31.09kg compared to 32.69kg in group B (P=0.222). Glycemic control was better in group B (P=0.023), whereas the control of systemic arterial pressure was better in group A (P=0.026). There were no significant differences in early lipid control and micronutrient deficiencies between the two groups. Conclusions: SG and GB were equally effective in promoting weight loss after 90 days. However, whereas SG was associated with better early remission rates for hypertension, GB was more effective in fasting blood glucose control but not in HOMA-IR and HbA1c levels. There was no difference in the protein or vitamin deficiencies of the two groups.