A unicornuate uterus is a rare congenital malformation of the female genital tract, which appears in about 1/1000 women and is characterized by significant anatomic variability. In the most common type, a noncommunicating rudimentary horn coexists with the unicornuate uterus. The diagnosis of this anomaly is usually delayed, as it remains asymptomatic until adolescence and its initial symptoms are atypical. As a result, it is often diagnosed after the appearance of severe complications, such as haematometra, endometriosis, infertility and ectopic pregnancy. We report a case of a teenage girl presenting with dysmenorrhoea, endometriosis and haematometra secondary to a noncommunicating rudimentary horn. The diagnosis of the anomaly was based on magnetic resonance imaging (MRI) and laparoscopy. The excision of the symptomatic rudimentary horn and the ipsilateral fallopian tube was also performed laparoscopically. A review of the literature follows, focusing mainly on the diagnosis and laparoscopic management of a unicornuate uterus and its complications in adolescence. Laparoscopy is an accurate diagnostic tool, which also carries significant advantages in effective surgical management of congenital uterine anomalies, especially in young women.