This review highlights recent advances in the understanding of the biosynthesis of the adrenal-specific steroid hormones, the mineralocorticoids and glucocorticoids. The genes, or complementary DNAs encoding each of the enzymes required for catalyzing biosynthesis of aldosterone and cortisol from cholesterol were all cloned before 1992-As each of the gene sequences and structures has become known, mutations have been found in patients with corresponding specific inherited disorders of steroid biosynthesis, simultaneously defining the genetic basis of the disorder and confirming thein vivorole of the enzyme. Isolation of the steroidogenic genes and characterization of their promoters is now leading to the identification of the transcription factors required for their expression.