The term adrenal cortex refers to the outer region and largest part of an adrenal gland. Adrenal cortex is divided into three distinct layers, namely, zona glomerulosa, zona fasciculate, and zona reticularis. The responsibility of each layer is to produce specific hormones. It is also the secondary site for the synthesis of androgens. Zona glomerulosa is the outermost layer of the adrenal cortex. This layer is the main site for the synthesis of aldosterone, a mineralocorticoid. The second zone, zona fasciculata is located between zona glomerulosa and zona reticularis. The basic function of this zone is to produce and secrete glucocorticoids, such as 11-deoxycorticosterone, corticosterone, and cortisol. The major hormone that stimulates cortisol secretion in humans is the ACTH that is released from the anterior pituitary. The third zone, zona reticularis is the innermost layer that produces androgens, namely, dehydroepiandrosterone (DHEA), DHEA sulfate (DHEA-S), and androstenedione (the precursor to testosterone) in humans. This book provides significant information on the pathology and biology of adrenal cortex. It will prove to be immensely beneficial to students and researchers in the field of endocrinology.