Serous cystadenomas of the pancreas are generally considered to be microcystic adenomas. Typical serous cystadenomas of the pancreas are encapsulated tumors composed of tiny cysts less than 2 cm in size showing sponge-like appearance with a central stellate scar or calcification on the cross-section. It has been recently reported, however, that serous cystadenomas may have macrocystic variants (major cysts more than 2 cm in size) that are radiologically indistinguishable from mucinous cystadenomas of the pancreas. We report the CT and MR imaging findings in a patient with mixed microcystic and macrocystic serous cystadenoma of the pancreas, indicating the histopathologic correlation. The mass was composed of two different types of cyst: multiple, small (<2 cm) with central calcification; and large (>2 cm) with peripheral calcification.