The fetal adrenal cortex is the central steroid modulator in the fetal placental complex. Its anatomic structure and physiology clearly identify it as a uniquely fetal organ that undergoes atrophy to a fraction of its intrauterine size after birth and assumes markedly different steroidogenic functions on the assumption of extrauterine life. Its importance as a regulator of maturation and parturition in normal gestation is just being understood. The fetal adrenal cortex no doubt plays major roles in the pathogenesis of some of the most important clinical problems currently faced in contemporary obstetrics. Continued research that provides a more complete understanding of this organ will serve as the major base for innovative diagnostic and therapeutic advancements of the future.