A case of adrenal cystic neuroblastoma (NB) detected by prenatal ultrasonography (US) is presented. The suprarenal mass initially showed pure cystic features on a variety of imaging studies such as US, computed tomography, and magnetic resonance imaging. Tumor markers were negative. The mass was suspected to be an adrenal hemorrhage rather than a NB. Three months later, although the diameter was unchanged, the thickness of the cyst wall seemed to have slightly increased. Surgical exploration revealed an adrenal cystic tumor and histology showed a NB in situ. Forty-five infants with prenatally detected NB were found in the English literature; about one-half of them were cystic NBs, and most had a favorable outcome.