SummaryA new adrenal scanning agent, Adosterol (131I-6β-iodomethyl-19-norcholest-5(10)-en-3β-ol) has been evaluated in three female patients with hypercortic-ism. In one case, characterised by recurrent adrenocortical hyperactivity after bilateral adrenalectomy, a remnant of adrenal tissue was detected. In two other cases, the presence of an adrenal tumour could be excluded. The scan made on the 6th day after the administration of Adosterol was found to be superior in quality to that made on the 13th day.