The 49, XXXXY syndrome is a rare sex chromosome polysomy, first described by Fraccaro and colleagues in 1960. The approximate incidence of this disorder is 1 in 85,000 male births. To date, >100 cases had been published in the literature. Patients with 49, XXXXY syndrome show some peculiar clinical features, such as mental retardation, facial dysmorphism, ambiguous genitalia, and multiple skeletal and cardiac defects. We report a new case of 49, XXXXY syndrome; the first Italian case to our knowledge.