Some environmental factors of possible aetiological importance for primary liver carcinoma (PLC) in males were analysed in a case-control study including 83 cases of hepatocellular carcinoma (HCC), 15 cases of intrahepatic cholangiocellular carcinoma (CC), 3 cases of haemangiosarcoma and 1 case of unspecified sarcoma in the liver--102 cases in total. Two matched controls were used in each case. One case with haemangiosarcoma was exposed to polyvinyl chloride. The case with unspecified soft-tissue sarcoma was exposed to phenoxy acids. A 4-fold increase in the risk of HCC was seen in alcoholics, and regular drinking gave a 3-fold increase in the risk. Exposure to organic solvents gave a 2-fold increase in the risk of HCC. No increased risk was observed for cases exposed to various other chemicals. Three cases of HCC had a previous diagnosis of porphyria acuta intermittens (PAI), versus no control. Six cases of HCC had a previous diagnosis of porphyria acuta intermittens (PAI), versus no control. Six cases with PLC had polyphyria cutanea tarda (PCT) which in 4 cases was related to alcoholism and in one case to haemochromatosis.