Fibrovascular polyps are rare, pedunculated, tumor-like lesions that are usually found in the esophagus; occurrence in the stomach is very rare. To our knowledge, sonographic and CT findings of a fibrovascular polyp in the stomach have never been reported. Here, we report a case of a fibrovascular polyp that was identified in the gastric antrum and prolapsed into the duodenal bulb. Sonography revealed a hyperechoic polypoid mass in the gastric antrum, which prolapsed into the duodenal bulb upon a change in the patient's position. CT also revealed a pedunculated polypoid mass with an inner fatty component.