Asymptomatic adrenal tumors are discovered more and more frequently with improving quality of diagnostic imaging. Treatment of these tumors, described as incidentalomas is controversial and depends on the one hand on the size of the tumor and on the other hand on morphological appearance in diagnostic imaging. In the literature a tumor size over 3 cm is in general regarded as an indication for operation, based on findings of Copeland et al. where the size of the tumor was correlated with malignancy. In the Department of Surgery in Mannheim 28 operations on adrenal incidentalomas have been performed between 1973-1993. In three patients a carcinoma was found. Four of the removed tumors each of them benign had a diameter smaller than three centimeters. An operation seems to be justified under certain conditions, even in small tumors, because potentially malignant tumors can undergo early and radical surgery. A general recommendation for treatment of the above mentioned tumors, depending only on size and morphology in diagnostic imaging, seems to be difficult. The decision for surgical therapy needs to be evaluated individually for every patient.