Purpose: To elucidate the dynamic features of CT scans in peripheral cholangiocarcinoma for thedifferentiation of this tumor from various primary hepatic neoplasms. Materials & methods: Materials were 24 casesof pathologically confirmed peripheral cholangiocarcinoma. Contrast enhancement patterns of central and peripheralportion of the masses were analyzed at three phase including arterial dominant(22), tissue equilibrial(24), andpostequilibrial(9). other associated CT findings and laboratory data were analyzed. Results: Serum total bilirubinwas almostly below 2 mg/dl(22/24), hepatitis B surface antigen was positive in only 9%, serum alphafetoprotein waselevated in 18%, carcinoembryonic antigen in 47%, cancer antigen 19-9 in 60%. In the arterial dominant image(22).50% of the cases showed peripheral hyperdensity and 50% total hypodensity. In the tissue equilibrial images(24).63% showed total hypodensity, 25% peripheral hyperdensity, and 13% total isodensity. In the postequilibrialimages(9), 45% showed peripheral hypodensity, 33% total hyperdensity, and 22% total hypodensity. The relative CTdensity of central portion of mass was higher in later phase than earlier phase. Associated findings were IHDdilatation(18) or stone(2), lymphadenopathy(11), ipsilateral lobar shrinkage(7), surrounding cystic mass(2),calcification within the mass(2) and choledochal cyst(2). Conclusion: Dynamic features of CT scans were useful forthe systematic differentiation of the peripheral cholangiocarcinoma from various primary hepatic neoplasm.