Incidentally discovered adrenal masses are common since the advent and application of sensitive noninvasive imaging methods. The significance of these so-called "incidentalomas" and the question of further evaluation or treatment remains elusive. This report describes a retrospective study of 86 patients with incidentaloma. Adrenalectomy was performed on 26 patients during initial admission. Histologically, two cortisol-producing adenomas, an adenoma with subclinical cortisol production, and two pheochromocytomas (all of the preceding detected during the preoperative hormonal evaluation), three cystic lesions, one myelolipoma, and one hematoma were found. One primary and two metastatic adrenal carcinomas were also found in this series. Sixty patients with a nonfunctioning incidentaloma smaller than 6 cm were observed in an average of 43 months with serial CT scans performed at 3, 9, and 18 months after the initial diagnosis. Enlargement of the mass was detected in two patients; both proved to be nonfunctioning adenomas. Based on these observations, it is concluded that the initial laboratory evaluation is mandatory in cases of incidentalomas, including parameters of adrenocortical and medullar function. Hormonally active incidentalomas and those suspected for malignancy should be treated surgically. Masses greater than 6 cm should also be removed. Smaller incidentalomas without endocrine activity or signs of malignancy should be followed by CT scan at 3, 9, and 18 months after the initial diagnosis.