An autopsy case of mucoepidermoid carcinoma of the liver associated with congenital cysts in a 78-year-old man was reported. The liver weighed 1,900 g, and there was a massive tumor of 11 X 10 X 6.5 cm in the left lobe with multiple sero-mucinous cysts. Histologically, the tumor cells consisted of four types of cells: mucus-secreting cells, squamous cells, intermediate cells, and oxyphilic cells. The variety of tumor cells quite resembled that of mucoepidermoid carcinoma of the salivary gland. The sero-mucinous cysts were lined with a single layer of cuboidal or columnar cells and were not communicated with the biliary ducts. Part of the cysts with benign lining cells was in continuity with tumor cells of the intermediate type. Discussion was made on the histogenesis of hepatic mucoepidermoid carcinoma in particular emphasis on the association of the congenital cysts.