Once considered variants of Klinefelter syndrome, 48,XXYY, 48,XXXY and 49,XXXXY are now recognised as clinically distinct syndromes with variable genital, developmental and medical presentation (Tartaglia, Ayari, Howell, D'Epagnier, & Zeitler, 2011). 49, XXXXY syndrome is one of the rarest sexual chromosome disorders, with an estimated incidence of 1:85000-100000 (Gropman et al.,2010). 49, XXXXY syndrome has a variable presentation with features often including genital malformations such as cryptorchidism, hypospadias and hypogonadism. They often have facial features such as coarse face, hypertelorism, epicanthic folds and upslanting of the palpebral fissures. Skeletal deformities may include radioulnar synostosis and microcephaly. Neurologic involvement is variable with the majority of these patients displaying severe intellectual disability (Qureshi & Thurairajan, 2007). MRI findings including changes in white matter and volume loss were described in previous literature (Hoffman, Vossough, Ficicioglu, & Visootsak, 2008). The severe cognitive, physical and developmental complications necessitate accurate and early diagnosis with early intervention to improve the patients' lifestyle and outcomes. The degree of developmental disability and genital malformations is not well described in the literature. This case report aims to describe the developmental and sexual findings in a patient with 49, XXXXY syndrome.