This report describes studies of a man suspected of having primary cortisol resistance. This conclusion is based on his high plasma cortisol levels and high 24-h urinary 17-hydroxycorticosteroid and cortisol excretion, plus the fact that he had no manifestations of Cushing's syndrome. Among family members tested, his mother also had hypercortisolemia. Both mother and son had high levels of unbound plasma cortisol, but their plasma ACTH concentrations were within the normal range. Both were partially resistant to dexamethasone adrenal suppression, and both had mild hypertension without hypokalemia. To study this apparent end-organ resistance to cortisol, we examined the glucocorticoid receptors in peripheral mononuclear cells. Using whole cell assays, glucocorticoid receptors in both patients were found to have reduced total binding capacity. We conclude that these two patients, members of the same family, have primary cortisol resistance accompanied by a reduced number of glucocorticoid receptors.