Liver is generally known as an organ which is most commonly involved by the metastic tumors. According to the tendency of using fine needle aspiration in the diagnosis of hepatic tumors, the differentital diagnosis between hepatocellular carcinoma and metastatic carcinoma frequently has been a main issue in the poorly differentitated cases, especially to the pathologists of Korea, an endemic area of hepatocellular carcinoma. Until now the problem has been usually solved by the comparison of cytologic characteristics of their tumor cells but not by background cytologic features which rarely have been studied. We observed the background cytologic features helpful for the differential diagnosis through the analysis of 20 cases who had confirmed primary cancer and were diagnosed as metastatic carcinomas in the liver by fine needle aspiration cytology. Twenty cases included 9 adenocarcinomas, 7 spuamous cell carcinomas, 1 small cell carcinoma, 1 carcinoid, 1 adenoid cystic carcinoma, and 1 renal cell cacinoma. Analysis of background cytologic features revealed that 77% of adenocacinoma cases showed benign mesenchymal components and hepatocytes and spuamous cell carcinoma cases disclosed benign mesenchymal tissue (71%) and necrosis (57%), Remaining cases showed variable combinations of benign mesenchymal component, necrosis, hepatocytes, and bile duct epithelial cells. No case revealed atypical hepatocytic naked nuclei, a useful cytologic finding of hepatocellular carcinoma. In summary, the background cytologic features more commonly observed in metastatic carcinomas than in the hepatocellular carcinoma were benign mesenchymal components, hepatocytes, necrosis, and bile duct epithelium. The endothelial cells and hepatocytic naked nuclei, two relatively specific findings of hepatocellular carcinoma were not observed except for renal ceil carcinoma. Above background cytologic features are thought to be helpful for the differential diagnosis between the hepatocellular carcinoma and various metastatic carcinomas in the poorly differentiated cases.