Determination of postnatal AMH levels in circulation has been used for decades when evaluating a child with ambiguous genitalia. We describe the age- and gender-specific changes of postnatal AMH serum levels to enable an appropriate clinical use of AMH assessment in pediatric endocrinology. In males, cord blood AMH is measurable at high levels (mean 148 (53-340) pmol/L), whereas AMH is undetectable (54%) or very low (95% CI: <2-16 pmol/L) in female infants. AMH is constant through childhood in both sexes, boys having approximately 35 times higher levels than girls with no overlapping between the sexes until puberty. Ambiguous genitalia due to impaired androgen secretion or action may be a result of various conditions with low, normal or high AMH. Furthermore, low AMH is a marker of premature ovarian failure in Turner Syndrome girls. Measurement of AMH is an important tool in assessing gonadal function in children. In this context, detailed normative data are essential.