The purpose of this paper is to report findings in post-MTX liver biopsies from 160 psoriatics treated with Methotrexate (MTX) in single biopsy and B. 68 patients with serial biopsies. At the time of liver biopsy the 92 patients had received a mehosis and six patients had fibrosis. Comparing these 7 patients with patients having normal liver histology (13 patients) revealed no statistically significant difference in cumulative doses of MTX, but a statistically significant higher admitted alcohol intake during MTX therapy (p less than 0.002) and an older age (p less than 0.01) in the patients with cirrhosis or fibrosis. in the 68 patients MTX had accumulated to a mean dose of 3940 mg (range 32k-8355 mg) at the time the latest liver biopsies were taken. Among the latest liver biopsies were 14 cirrhosis (21 per cent, 95 per cent confidence limits: 12-32 per cent) and 16 fibrosis (24 per cent, 95 per cent confidence limits: 14-35 per cent). The 14 patients with cirrhosis when compared to patients with normal histology (9 patients), had taken an equal total dose of MTX at the latest liver biopsy, but had consumed a statistically significant higher amount of alcohol (p less than 0.05) during MTX therapy and also tended to be older (p less than 0.006). Comparison of a material A and B indicates that the prevalence of cirrhosis and fibrosis among MTX treated psoriatics increases rapidly beyond a cumultative dose of two to four grams of MTX. No MTX treated psoriatics should thus be allowed to pass this dosage range without having a liver biopsy performed.