Four patients with adrenal tumors in whom prolonged fever was the foremost symptom are presented. Two of the patients had nonfunctional adrenocortical carcinoma, one had a pheochromocytoma without adrenergic hyperactivity, and in the fourth, an aldosteronoma was found. Only in 1 case was the tumor (pheochromocytoma) resectable and this patient became afebrile post surgery. A review of the literature revealed that fever is encountered in 6-10% of cases with adrenal tumors, sometimes as the first manifestation of disease. However, a survey of the large series of fever of unknown origin revealed no mention of adrenal tumors in that group of solid tumors which many cause prolonged fever.