Incidental radiologic diagnosis of clinically silent adrenal masses is reported with increasing rates. Between 1981 and 1994 we observed 30 patients with "incidentaloma": for each of them a careful hormonal and instrumental evaluation was obtained. 24 patients were surgically treated. No significant biochemical alterations were observed; ETG, TC and RMN had a sensitivity of 86%, 93% and 83%, respectively. At seleno-cholesterol scintigraphy 5 incidentalomas (all adenomas) had a concordant pattern and 5 (none of these adenoma) had a discordant pattern. MIBG scintigraphy showed an uptaking ganglioneuroma. The observed histotypes were: 10 adenomas, 3 cysts, 1 hematoma, 1 myelolipoma, 1 angiomyolipoma, 1 ganglioneuroma, 1 ganglioneurofibroma, 1 paraganglioma, 1 aspecific granulomatous necrosis, 4 cortical carcinoma and 3 metastatic lesions. We did not observe any postoperative acute adrenal failure. The main problem raised by incidentalomas is to define their nature; hence the need of a careful hormonometabolic, morpho-functional and instrumental evaluation. The available diagnostic procedures, even when combined, cannot always define if an incidentaloma is a benign or a malignant lesion: in the current clinical practice, the size of the mass is still the most important criterion to define a therapeutic approach. Surgical excision is mandatory in presence of an hormonal production, even subclinic, and/or a large size of the mass (over 5 cm). If the tumor size is less than 5 cm, an aggressive strategy may be chosen in selected low-risk patients, because of the low morbidity of adrenalectomy. In our experience, the transperitoneal subcostal approach has been adopted routinely with good results.