The serous cystadenoma of the pancreas is a rare lesion that is usually found incidentally. It is mostly observed as a spongy microcystic mass but rare variants such as macrocystic, unicystic, or multicentric are also seen. We recently experienced a unique case of unicystic serous cystadenoma mimicking a pseudocyst. It was grossly a unilocular cyst with surrounding dense fibrosis resembling a pseudocyst. Microscopically, the cyst was partly lined by low columnar-to-cuboidal cells with clear cytoplasm containing glycogen.