CASE REPORT: We report on the laboratory, clinical, radiologic and histological findings of a 44-year-old male patient who was hospitalized with the clinical signs of Cushing's syndrome. The laboratory findings were suggestive of an adrenal genesis. Abdominal computed tomography revealed macronodular hyperplasia of both adrenal glands. Specific endocrinological tests demonstrated an increased secretion of cortisol during adrenergic stimulation which, however, was absent following beta-blocker medication. This would seem to point to an aberrant, beta-receptor-mediated regulation of cortisol secretion as being the cause of increased cortisol production. ACTH-independent bilateral macronodular adrenocortical hyperplasia was also noted in the patient's mother. Neither the father nor the brother were affected by the disease. Apart from one case of familial appearance involving mother and daughter previously reported in the literature, this is the second description of a familial appearance and the first case involving mother and son. The patient underwent a left-sided adrenalectomy. Quick postoperative normalization of S-cortisol day profile and excretion of free dU-cortisol were noted under supportive temporary blockade of beta-receptors. In the further course, meanwhile spanning 2 1/4 years, a low basal cortisol secretion of the right adrenal gland has been observed, together with a lack of suppressibility in the dexamethasone suppression test. CONCLUSION: In the presence of mild clinical signs of adrenocortical insufficiency, matutinal administration of 5 mg hydrocortisone has proven sufficient for the past 6 months to reestablish a physiologic S-cortisol day profile with morning peak.