Introduction: Bariatric surgery is a procedure to reduce weight in the long term in patients with obesity. The objective of this study was to evaluate ghrelin levels and weight reduction according to the type of bariatric surgery, comparing the single anastomosis bypass and the sleeve-forming gastrectomy. Materials and Method: Cohort study that included 50 patients with obesity, 22 Mini-Bypass and 28 gastric sleeve. Body weight and ghrelin concentrations were evaluated in the presurgical stage, on day 7 and in months 1, 3 and 6 after surgery. Results: Of the total of patients, 86% had > 50% excess weight loss (PEPP) at 6 months. The concentration of ghrelin decreased within the first week of the intervention. At 6 months, greater reduction of ghrelin was observed in patients with gastric sleeve (4636 ± 2535 vs 1340 ± 1001 pg/mL, p < 0.0001). The PEPP in patients with Mini-Bypass was superior, compared to gastric sleeve. Conclusion: The comparison between the techniques indicated that, after 6 months of post-surgical evolution, patients with Mini-Bypass had a greater reduction in body weight and ghrelin levels, compared to the gastric sleeve group. Ghrelin concentration is a variable that participates in weight control; however, the type of surgical approach is probably more related to weight loss in these patients. Key words: bariatric surgery; vertical sleeve gastrectomy; ghrelin