Carcinoid tumors are slow growing submucosal tumors with metastatic potential that arise from enterochromaffin cell. The annual incidence of carcinoid tumor is 2 to 3 per 100,000. Carcinoid tumor of duodenum is very rare with an incidence of about 8% among gastrointestinal carcinoid tumor. As a endoscopic examination and immunohistochemical stain are developed, an rate of detection is increasing. Among the possible factor of metastatic prediction, tumor size >10 mm, central depression or ulcer, invasion below submucosa, lymphatic or venous invasion are associated with higher metastatic potential. Specially, in case of tumor size <10 mm, in duodenum, there is no report of metastasis to liver in Korea. But, recently, we experienced a rare care of duodenal carcinoid measured by less than 10 mm with liver metastasis. Thus, we report here this case with a review of literature.