Introduction. Herlyn-Werner-Wunderlich syndrome is a complex abnormality in the development of the female genitourinary system, which includes the uterus didelphys, the longitudinal septum of the vagina with obstruction of one half and ipsilateral agenesis of the kidney. The exact prevalence of this syndrome is unknown, but some publications indicate that the frequency of this pathology ranges from 0.16 to 10% among all female genital tract malformations. Clinical case. The article presents a clinical case of a 14-year-old patient with Herlyn-Werner-Wunderlich syndrome, who was diagnosed and treated in time. Diagnostic approaches and treatment were also discussed. The patient complained about progressive dysmenorrhea from the age of menarche within 6 months, which became intolerable and did not pass after receiving symptomatic therapy. Ultrasound examination of the pelvis and kidneys revealed a combined anomaly of the genitourinary system: the uterus didelphys, right-sided hematocolpos and hemato cervix, agenesis of the right kidney. Magnetic resonance imaging of the pelvic organs and abdominal cavity confirmed that the patient had Herlyn-Werner-Wunderlich syndrome. Excision of the longitudinal septum of the vagina with the formation of a single vagina was carried out. About 200 ml of thick, dark blood was released during the excision of the septum from the blind right vagina.. There were neither intraoperative nor postoperative complications. The patient was discharged home in a stable condition on the 5th day. Twelve days after discharge from the hospital, the patient had their period that lasted for 6 days and was painless. The patient had no more complaints. Conclusions. Early diagnosis of Herlyn-WernerWunderlich syndrome and its surgical correction will prevent serious gynecological complications. The combined use of expert ultrasound and magnetic resonance imaging plays a decisive role in the diagnosis of this syndrome. The key to success in the management of patients with HerlynWerner-Wunderlich syndrome is the coordinated work of a multidisciplinary team with the involvement of a pediatric gynecologist, urologist, radiologist, ultrasound specialist and anesthesiologist. In cases of intrauterine diagnosis of agenesis of one kidney or other pathology of renal development in female fetuses, a differential diagnosis with Herlyn-Werner-Wunderlich syndrome should be made later before the onset of menarche.