AIM To prospectively evaluate the postoperative morbimortality and weight loss evolution of patients who underwent a laparoscopic sleeve gastrectomy (LSG) as a primary bariatric procedure during 5 years of follow-up. METHODS Since 2006, data from patients undergoing a highly restrictive primary LSG have been prospectively registered in a database and analysed. Preoperative co-morbid conditions, operating time, hospital stay, early and late complications rate and evolution of weight loss after 5 years of follow-up were analysed. RESULTS A total of 156 patients were included, 74.3% of whom were women. The mean age was 43.2 +/- 13.1 years and the mean body mass index (BMI) was 41.5 +/- 7.9 kg/m(2). Seventy patients (44.8%) presented a BMI under 40 kg/m(2). The mortality rate was 0%. The leakage rate was 1.2%, and the total 30-d morbidity rate was 5.1% (8/156). With a mean follow-up of 32.7 +/- 28.5 (range 6-112) mo, the mean percent of excess of weight loss (% EWL) was 82.0 +/- 18.8 at 1 year, 76.7 +/- 21.3 at 3 years and 60.3 +/- 28.9 at 5 years. The mean percent of excess of BMI loss (% EBMIL) was 94.9 +/- 22.4 at 1 year, 89.4 +/- 27.4 at 3 years and 74.8 +/- 29.4 at 5 years. Patients with preoperative BMI less than 40 kg/m(2) achieved greater weight loss than did the overall study population. Diabetes remitted in 75% of the patients and HTA improved in 71.7%. CPAP masks were withdrawn in all patients with obstructive sleep apnoea. CONCLUSION LSG built with a narrow 34 F bougie and starting 3 cm from the pylorus proved to be safe and highly effective in terms of weight loss as a stand-alone procedure, particularly in patients with a preoperative BMI lower than 40 kg/m(2). Key words: Sleeve gastrectomy; Morbid obesity; Bariatric surgery; Obesity surgery; Laparoscopy; Long-term results; 5-year results (C) The Author(s) 2017. Published by Baishideng Publishing Group Inc. All rights reserved.