Addison's disease, or primary adrenal insufficiency, results in glucocorticoid and mineralocorticoid deficiency. Orthostatic hypotension, fever, and hypoglycemia characterize acute adrenal crisis, whereas chronic primary adrenal insufficiency presents with a more insidious history of malaise, anorexia, diarrhea, weight loss, joint, and back pain. The cutaneous manifestations include darkening of the skin especially in sun-exposed areas and hyperpigmentation of the palmar creases, frictional surfaces, vermilion border, recent scars, genital skin, and oral mucosa. Measurement of basal plasma cortisol is an insensitive screening test. Synthetic adrenocorticotropin 1-24 at a dose of 250 microg works well as a dynamic test. Elevated plasma levels of adrenocorticotropin and renin confirm the diagnosis. Treatment involves replacement of the deficient hormones.