A 39-year-old woman was referred to our hospital due to left abdominal mass which was incidentally pointed out by computed tomographic (CT) scan. She had no symptoms. Abdominal enhanced CT showed an 85 mm solid mass, which had clustered calcifications and was enhanced weakly. Magnetic resonance imaging showed a relatively well-circumscribed mass 125 mm in maximum diameter, in the left kidney. The left adrenal gland could not be identified. An endocrinological examination was done. In the 24-hour specimen of urine, dopamine and vanillylmandelicacid levels were abnormally high. We surgically removed the tumor, because malignancy including adrenal carcinoma was not completely excluded. An additional 1cm tumor which mimics lymph node metastasis along the aorta was found during the operation and removed. Postoperative histopathological findings revealed the tumor clearly distinguished from the adrenal gland and was composed of mature nerve fibers and ganglion cells. The other tumor had the same histology without any lymph node tissue. On the basis of this finding, it was diagnosed as multifocal retroperitoneal ganglioneuroma.