Abnormal result of liver function tests (elevated levels of AST, ALT activity) and/or abnormal haematological values (low platelet counts, leucocytosis, relative lymphocytosis) were observed in 49 of 200 workers exposed to toluene and/or xylene vapours for 5-20 years. Thirty of the affected workers were treated per os with Legalon (MADAUS, FRG) t.i.d. for 30 days. The remaining 19 were left without treatment. Under the influence of Legalon the liver function tests and the platelet counts significantly improved. The leukocytosis and relative lymphocytosis showed a nonsignificant tendency of improvement.