Sixteen cases of newly diagnosed Addison disease were studied by CT scan. An initial diagnosis was performed according to the clinical data of each patient, and a second diagnosis after examining the abdominal CT scan. According to the second diagnosis there were six patients with primary adrenal failure of probable autoimmune origin, six tuberculosis, two metastatic, one undetermined and one hemorrhagic. The second diagnosis coincided with the first one in 10 cases (62.5%), but was different in six cases (37.5%). Information obtained by CT scan modified the therapeutic attitude in 4 cases (25%). The main morphologic patterns of adrenal glands in CT scan (atrophy, calcification and enlargement) are commented as well as the importance of CT scan in the study of the more common etiologies of Addison's disease (tuberculosis, autoimmune, neoplastic metastasis and hemorrhage). It is concluded that the information obtained by CT scan is important in the etiological diagnosis of Addison disease and it is advised to perform it in all newly diagnosed cases.