Ulcus vulvae acutum is a rare clinical condition characterized by the presence of multiple acute painful genital ulcers of non-venereal origin associated with systemic symptoms in young women. The aetiopathogenesis of the disease is not fully understood, although recent reports have associated it with the Epstein-Barr virus. Diagnosis is difficult and generally made by exclusion after venereal diseases, and autoimmune, inflammatory, traumatic, and neoplastic causes. We describe a case of adolescent female with an episode of ulcus vulvae acutum associated with infectious mononucleosis. The diagnosis was supported by the clinical symptoms, elevated circulating levels of liver enzymes, positive EBV serology, cervical and inguinal lymphadenomegaly, and hepatosplenomegaly. The patient presented a history of aphthous stomatitis. Negative Pathergy test and the absence of any other related symptoms allowed us to exclude the Behçhet syndrome. Lesions healed with no sequelae or recurrences.