Micro-vascular patterns in the human adrenals in the course of development and in adults were visualized by postmortal angiography and examined in relation to adrenocortical lesions. The terminal unit of the arterial blood supply to the adult adrenal cortex consists of the capillary dome in the glomerulosa with brush-like capillaries perforating the fasciculata, while the zona reticularis receives arterial blood from the arteriae medullae. Therefore, the proper fasciculata is situated in the utmost periphery of the arterial circulation. The capillary dome as the terminal unit of the arterial blood supply plays an important role in precipitating various adrenocortical lesions. Capillary dysarrangement was rather indistinct in nodular hyperplasia, but it was remarkable in solitary intracortical nodules receiving several arterioles. In fetuses and newborns, cortical lesions appeared diffusely because they lacked capillary domes. The cortico-medullary vein drained from the glomerulosa into the medullary vein, while the emissary vein was demonstrated as large communications between the capsular and medullary veins. A circulatory blockade between the permanent and fetal cortex proceeding with fetal maturity was found responsible for neonatal hemorrhage involving exclusively the fetal cortex. The similarity of the adrenal vascular pattern of anencephalic newborns to that of normal infancy was ascribed to early involution of the fetal cortex in anencephalus.