INTRODUCTION Endometriosis affects several aspects of a woman's life, including sexual function, but which specific aspects of sexual function remains unclear. METHODS A cross-sectional study was performed involving 1001 women divided into two groups, according to the presence or absence of endometriosis. We assessed sexual function, anxiety and depression of patients and correlated these findings with symptoms, locations and types of endometriosis and the affected domains of sexual function. Eighteen completed the forms incorrectly, 294 women (29.9%) were excluded due to severe anxiety and depression. One hundred and six patients had symptoms that could have any relation to endometriosis, so they were also excluded. The final cohort was composed of 254 patients with endometriosis and 329 patients without the disease. Sexual function score was assessed using the female sexual quotient (FSQ); Beck inventories were used to assess anxiety and depression. RESULTS Patients with endometriosis were affected in all phases of sexual response: desire, sexual arousal, genital-pelvic pain/ penetration and orgasm/ sexual satisfaction. In the overall assessment, 43.3% of patients with endometriosis had sexual dysfunction, while the population without endometriosis sexual dysfunction occurred in 17.6% of women. CONCLUSIONS Patients with endometriosis have more than twice sexual dysfunctions as compared to women without the disease.