21-hydroxylase deficiency (21-OHD) accounts for the cause of 90-95% of congenital adrenal hyperplasia (CAH) cases. The world incidence of 21-OHD is 1: 20, 000 to 1: 10, 000 live births.Prevalence of CAH trends to be high due to frequent consanguineous and first cousin marriages and underestimation because of stigmatization. A range of clinical phenotypes including salt-wasting, simple virilizing and nonclassic forms is emerged due to the variable residual 21-hydroxylase enzyme activity in CAH.Enzymatic defects in steroid biosynthesis pathway leads to accumulation of the metabolic precursors and shifting to androgen synthesis.Ambiguous genitalia appear in infant girls.Basically, salt-wasting form occurs between first and third week after birth. Because of nonspecific symptoms, an accurate diagnosis is often delayed so that males with classic form are at serious risk of morbidity (including neurological damage or intellectual disability) and mortality.