Disorder of sexual development or disorder of sex differentiation (DSD) refers to the inconsistency between karyotype and gonad phenotype and/or gonad anatomy in neonates and is manifested as the difficulty in identifying neonates' sex. According to the karyotype, DSD is classified as 46, XY DSD, 46, XX DSD, and sex chromosome DSD. A combination of detailed medical history, physical examination, and laboratory and imaging examinations is required for the diagnosis and comprehensive assessment of neonatal DSD and the determination of potential causes in clinical practice. Sex identification can only be made after all diagnostic evaluations have been completed. Sex identification of DSD neonates is influenced by various medical and social factors, including genotype (karyotype), sex hormones (levels of testosterone, dihydrotestosterone, and adrenal steroids), sex phenotype (appearance of internal and external genitals), reproduction (fertility potential), feelings of their parents, and even social acceptance and religious customs. A team with multidisciplinary cooperation is required, and patients must be involved in the whole process of sex identification. The major task of neonatal physicians for DSD is to assess the condition of neonates and provide management.