Disorders of sex development are a rare and heterogeneous group of congenital anomalies, characterized by an aberrant development of the chromosomal, gonadal or phenotypical sex. Treatment of DSD is concentrated in multidisciplinary centers. Although most patients present at neonatal age with genital ambiguity, some are diagnosed at a later age due to symptoms like delayed puberty. Long-term follow-up on physical and psychosexual functioning and quality of life are scarce and inconsistent, but often unfavorable; prospective data on these aspect are lacking. International collaboration on both research and clinical aspects are important to improve diagnosis and facilitate an evidence-based treatment; meanwhile the first European networks have been established.