BACKGROUND Mayer-Rokitansky-Küster-Hauser (MRKHS) syndrome refers to congenital hypoplasia/aplasia of the uterus, the cervix and the upper 2/3 of the vagina, in females with normal ovaries and fallopian tubes, secondary sexual characteristics and 46 XX karyotype. This condition originates from abnormal development of Müller's paramesonephric ducts in the early stages of embryonic development. Kidney agenesis or malformations are the most commonly associated with unilateral kidney agenesis. Ovaries may be ectopic in 16-19% of MRKHS patients. Primary amenorrhoea, due to the absence of the uterus, is the most common presentation. Female karyotype confirmation is mandatory to differentiate it from complete androgen insensitivity syndrome and 17-alpha-hydroxylase deficiency. The management of MRKHS is multidisciplinary in order to encompass psychological, medical and surgical issues. METHODS A four-year-old girl, presented to the emergency department complaining of left groin swelling noted 2 days earlier. The patient had recently been evaluated for an episode of acute abdominal pain and vomiting, with a final diagnosis of right ovarian torsion. At that time, the ultrasound imaging was not able to identify the left kidney, the left ovary and uterus. Surgical abdominal exploration confirmed the right ovarian torsion and was not able to identify the left kidney and the left ovary. Only a remnant of the uterus was present. Therefore, the right ovary was removed, and a diagnosis of MRKHS was made. Ultrasound imaging showed a left inguinal hernia. The hernial sac consisted of a solid oval vascularized formation suggestive of an annexe. The patient underwent a surgical procedure to correct the left inguinal hernia. In the operating setting, the presence of a vascularized, ectopic ovary carrying the tuba inside the hernial sac was observed. CONCLUSIONS In front of a patient with ovarian torsion and anatomical features suggestive of MRKHS, both the ovaries should always be searched for, with a high suspicion threshold for extrapelvic ovary. Identifying the ectopic ovary, in this case, helped to preserve patient fertility, avoiding a possible torsion.