Aminophenazone, phenazone, propyphenazone, and paracetamol given to female Wistar rats in a dose of 3 mmol/kg decrease the GSH content in the liver by 24, 18, 58, and 24 per cent, respectively. After the repeated administration (5 days) only aminophenazone depletes the hepatic GSH. The pretreatment with phenobarbital or cobaltous chloride has an influence only on the effect of propyphenazone. Hepatotoxins cause more extensive hepatotoxic alterations than the drugs investigated, however, their influence on the hepatic GSH level is negligible. Therefore it can be concluded that a temporary GSH depletion is not always linked with a hepatotoxic effect.