Twenty-two cases of primary hepatic tumours (16 hepatocarcinoma and 6 cholangiocarcinoma) have been studied by immunoperoxidase technique, for the presence of Epithelial Membrane Antigen (EMA). All 6 cases of cholangiocarcinoma showed positive reaction for the presence of EMA while 14 out of 16 hepatocarcinoma were completely negative. In two cases of hepatocarcinoma focal positive cells were present. The results obtained suggest that EMA could be of valuable use, in surgical pathology, for discriminating hepatocarcinoma from cholangiocarcinoma.