Background: Sleeve gastrectomy is a restrictive procedure for treatment of obese patients with different body mass index (BMI) and presents good results in terms of a reduction of percentage of excess weight loss and BMI. There is no consensus which is the optimal technique regarding to the diameter of the gastric tube, but a capacity of 100-120 ml has been suggested. In this prospective study, we compare the gastric capacity evaluated with barium sulfate or computer-aided tomography (CAT) scan early and 24 months after operation compared to the changes in body weight and BMI reduction in a small group of 15 consecutive patients submitted to sleeve gastrectomy. Methods: Fifteen successive obese patients submitted to laparoscopic sleeve gastrectomy were included. They were studied in order to measure the residual gastric capacity with barium sulfate and CAT scan early (3 days) and late (2 years) after surgery. Results: The early postoperative gastric volume was 108±25 ml (80-120 ml) and