55-year-old man presented with upper abdominal discomfort. A CT scan revealed a well-defined 4-cm calcified mass arising from the right adrenal gland. After 6 months the tumor had grown to 8 cm, but all laboratory data remained normal. An adrenalectomy was performed because of suspected malignancy. Histopathologic examination confirmed the diagnosis of adrenal neuroblastoma. This type of tumor is very rare in adults. It may present with nonspecific symptoms and be detected incidentally by ultrasonography. Findings on both CT and MRI are nonspecific. Calcification is not a reliable diagnostic finding. It should keep in mind that any adrenal tumor without specific clinical manifestations has malignant potential; therefore regular CT follow-up is necessary.