A left adrenal incidentaloma was found by abdominal ultrasound and computed tomography (CT) in a 53-year-old woman who had a history of non-insulin dependent diabetes mellitus. Abdominal CT showed a well-circumscribed adrenal mass (5.5 x 4.5 x 3.5 cm) with low density (32HU) on precontrast scan and heterogeneous enhancement on postcontrast scan. Laboratory examinations revealed a nonfunctional adrenal tumor. As the malignant potential of the tumor could not be ruled out, the patient underwent hand-assisted laparoscopic adrenalectomy. Postoperative recovery was uneventful, and pathologic examination revealed leiomyoma.