11 beta-hydroxyandrostenedione is a naturally occurring steroid that is primarily, if not strictly, produced in adrenal tissue. It is biosynthesized in the androgen arm of the adrenal steroidogenesis pathway and subsequently metabolized by steroidogenic enzymes in vitro, serving as precursor to recognized and novel androgenic steroids. In diseases such as Cushing′s syndrome, adrenal-originated hyperandrogenism, and congenital adrenal hyperplasia, plasma 11β levels are very high. Plasma 11β concentration is very low in congenital 11-hydroxylase deficiency and adrenal insufficiency. 11 beta-hydroxyandrostenedione was evaluated as a sensitive marker of adrenal androgen excess suggesting its unique diagnostic use.