Introduction. Pelvic pain syndrome associated with bladder pain syndrome is common in women with endometriosis (E). Bladder involvement with E is often unrecognized. Such women are treated for a long time from cystitis. International studies show that in the case of chronic pelvic pain associated with a pain bladder syndrome, simultaneous laparoscopy and cystoscopy under the same anesthesia is recommended as the most optimal method of diagnosis and treatment. Material and methods. A case-control study was carried out on 318 infertile patients hospitalized in IMSP SCM NR.1 during 3 years, with the diagnosis of E confirmed laparoscopically. Results. In 55 women (17.3%), E of the bladder was found, which the gynecological team only stated without surgical treatment. 58% of these patients were repeatedly treated for chronic cystitis due to the presence of bladder pain syndrome and hematuria. The rest of the women were asymptomatic. In 20% of patients with E of the bladder with secondary infertility, during pregnancy there were hydronephrosis and repeated pyelonephritis, which required stenting of the ureters, which may be an indirect sign of ureteral E. Conclusions. Thus, the presence of bladder pain syndrome in young women with infertility may be a sign of deep E, which is an indication for a multidisciplinary approach to reduce diagnostic and therapeutic errors.