Objective: To determine the clinical and biochemical characteristics, as well as the complications of bariatric surgery in 18 months of follow-up in a highly complex hospital, between 2012 and 2016. Methods: A descriptive, retrospective study was performed in patients undergoing bariatric surgery (gastric by-pass or gastric sleeve), where the clinical and biochemical characteristics, as well as the complications and post-intervention changes were evaluated in a before-after analysis. Results: Fifty nine patients were studied, 89.8 % were women, with an average age of 41.8 ± 10,8. The 76,3 % underwent gastric bypass and 23.7 % gastric sleeve. The mean percentage of weight lost at 18 months was 81 % ± 22. There was a significant reduction in abdominal circumference. 100 % of patients experienced changes in multimorbidities Conclusion: We found a significant decrease in the percentage of body mass index. In addition, a change in comorbidities and modification in biomarkers was observed. There was no post-operative mortality 18 months after surgery.