A recent case-control study on 577 lichen planus (LP) patients and 1008 controls confirmed that LP patients may significantly associate with a chronic liver disease (CLD) which is independent from drug or alcohol intake and has some connection with hepatitis B virus (HBV) infection. The study, however, failed to define the nature of CLD. This has been investigated through the clinical and laboratory features of 50 patients with LP and impaired liver function tests. Overall, the laboratory signs of cell necrosis prevailed over those of cholestasis and a good relationship with the HBV and HCV infections was found. Ninety percent of patients with LP and CLD had antibodies to one or another of the major viruses involved in infectious hepatitis. No patient had anti-liver kidney microsomal antibodies type 1. Liver biopsies were done in 12 cases and mostly revealed a chronic active hepatitis evolving into cirrhosis. No evident cases of primary biliary cirrhosis were found. It appears that LP associated CLD is post-viral in nature.