Objectives: Considering the prevalence of endometriosis in reproductive-age women and its negative impact on life quality, the authors of the present research intended to evaluate the impact of clinical treatment on the sexual function of patients with deep infiltrating endometriosis treated at the Endometriosis and Chronic Pelvic Pain Clinic of HSPE-FMO. Methods: A prospective and comparative observational study was conducted between May 2015 and July 2019 in which data from 43 patients with presumed deep endometriosis were analyzed, including age, parity, surgical and obstetric history and Female Sexual Function Index (FSFI questionnaire). Statistical analysis was performed using multiple regression in order to compare the variables. Results: The mean age of the women who were studied was 39.16 years; all patients were symptomatic and most had rectosigmoid endometriosis (65,1%). The median FSFI total score before treatment was 25.06, with 60,5% of the women classified as having a sexual dysfunction. There was a risk for sexual dysfunction to become permanent following clinical treatment when this dysfunction was established previously. The Poisson multiple regression showed that sexual dysfunction before treatment was associated with a lower FSFI total score after treatment and dysfunction before treatment had a direct correlation with final score smaller than 26.55. Considering the FSFI total scores before and after clinical treatment, there was no significant difference in the improvement rate between groups. Conclusions: Most patients did not show improvement in sexual function after clinical treatment.