A 45 day old boy presented with progressive abdominal distension, tarry stools and anemia. A plain roentgenogram of the abdomen showed irregular, coarse calcifications in the left upper quadrant. The ultrasonography and computerized tomography of the abdomen revealed a large heterogeneous tumor with calcified parts in the left hemiabdomen. At operation, a 12 cm x 11 cm x 10 cm, multilobular, exogastric and endogastric tumor, including a portion of the anterior wall of the stomach, was extirpated. The pathological examination revealed a gastric teratoma with immature neural elements. Eight years after the total excision of the tumor there has not been any recurrence. This study includes a review of 88 cases (including the present case) of gastric teratoma reported in the English and Japanese literature.