Two-hundred and eighty-six liver biopsies were performed in 139 psoriatics on treatment or considered for treatment with methotrexate. In 56 psoriatics included in this study both pre- and post-methotrexate biopsies were performed, the average methotrexate dose being 936 mg. None of the data showed statistically significant differences between pre- and post-methotrexate biopsies, with the exception of an increase in fattly infiltration, found when comparing all pre-methotrexate biopsies with the total number of latest post-methotrexate samples. As expected, alcohol seemed to be significantly associated with liver fibrosis in pre-methotrexate biopsies. An patients, although potassium arsenite alone has not been proved to be the cause of liver damage among psoriatics included in this study. While only 1 of 22 psoriatics with a total normal biopsy had been on arsenite, 6 of 18 of the same group of psoriatics who had fibrosis had been on this drug earlier. Although no statistically significant differences related to fibrosis and cirrhosis could that in three cases liver cirrhosis did appear in a biopsy from a methotrexate-treated psoriatic who had signs of fibrosis of cirrhosis in a pre-methotrexate biopsy. This incidence is low in relation to the total number of patients treated. The relatively low incidence of cirrhosis found in the present study, as in earlier studies by our group is believed to be due to the use of an intermittent dosage schedule. The study showed that early fibrosis and cirrhosis seem to appear, with very minor abnormalities in laboratory results. This finding indicates the necessity of performing liver biopsies in the control of psoriatics on long-term methotrexate therapy. The difference between biopsies from psoriatics and liver biopsies from control patients may indicate that severity of disease may be a complicating factor in the pathogenesis of the liver damage.