Abstract Disclosure: H. Tovar Cortes: None. Introduction: Therapeutic approach to gender dysphoria includes surgical interventions as part of the gender affirmation process.To make these procedures safe, it is recommended for the patient to have a normal BMI (body mass index). Obesity can increase the risk of complications during the perioperative period. To date, no studies have been published in Colombia documenting the results, and complications in patients undergoing gender affirmation surgery, and the relation to BMI. Case series A case series of patients diagnosed with gender dysphoria and multidisciplinary treatment is presented. Patients undergoing a gender affirmation surgical procedure, both in the context of transition from man to woman and from woman to man, who presented post-surgical complications are described. An analysis of the anthropometric measurements obtained through bioelectrical impedance analysis (BIA) of each of the patients was carried out; including weight, height, and BMI, with the objective of describing the surgical complications that occurred, as well as the categorization according to BMI range, and its possible correlation. From a database of 121 records of patients brought to a medical-surgical board for approval of gender affirmation procedures, a total of 78 patients were included, of which 33 presented post-surgical complications; 37 patients underwent feminization surgeries and 41 masculinization surgeries. In patients with post-surgical complications, it was found that 3% had a BMI less than 20 kg/m², 47% of the population had a BMI between 20 and 24 kg/m², 28% had a BMI between 25 and 29 kg/m², and 9 % of patients had a BMI grater than 30 kg/m². Most frequent complications were derived from thoracic masculinization surgery, highlighting suture dehiscence (7 cases), pectoral collections (6 cases) and tension hematomas (2 cases). All patients had in common post-surgical complications secondary to thoracic masculinization and BMI within normality. Conclusions Overweight and obesity are associated with an increase in surgical complications. Therefore, it is recommended that patients undergoing gender affirmation interventions should have a normal BMI, with the aim of reducing it, and achieving better surgical results. However, in our study, it was evident that these complications occurred predominantly in patients with BMI within normal range. These results could suggest that obesity is not associated with a significant increase in post-surgical complications. This provides important bases to carry out new studies that allow confirming these findings and bringing them to clinical practice. More evidence will reduce treatment barriers in these patients, allowing comprehensive treatment, and thereby improving the quality of life and biopsychosocial dysfunction of individuals with this condition. Abbreviations Body mass index (BMI), Bioelectrical impedance analysis (BIA) Presentation: 6/3/2024