Cortisol secretion in ACTH-independent primary adrenal Cushing's syndromes was previously believed to be autonomous. In most cases, the pathophysiology of the disease was largely unknown. However, recent work by our group and others have shown that these cortisol-producing adrenocortical tumors may be under the control of inappropriate, illicit or ectopic hormone receptors. This review provides a rapid overview of the physiology of the normal adrenal cortex and outlines recent findings supporting the hypothesis that cortisol production may be regulated by a diversity of abnormal or ectopic hormone receptors in primary adrenal Cushing's syndrome.