The incidental discovery of adrenal masses during modern diagnostic imaging is a common occurrence. These masses form part of a long differential diagnostic list; most often, they are benign adrenal adenomas, but their discovery requires a clinical evaluation that is sufficiently broad to exclude clinically silent endocrine disease, metastases to the adrenal gland in patients with suspected or known malignancies, and rare adrenocortical carcinomas. CT, MRI and nuclear medicine approaches have all been used to evaluate incidentally discovered adrenal masses. Each technology provides information that contributes to the noninvasive characterization of the majority of these neoplasms. Understanding of the modalities used to assess an unanticipated adrenal mass allows for more rapid diagnosis and cost avoidance in a condition that has been referred to as a 'disease' of modern imaging technology.