A 69-year-old man developed cholestatic liver enzyme disturbances three and a half weeks after starting treatment with acenocoumarol because of a deep venous thrombosis in his leg. Serological testing showed no signs of recent viral infections. A presumptive diagnosis of hepatotoxicity caused by the use of acenocoumarol was made and the anticoagulant was replaced by low molecular weight heparin. Three weeks after withdrawal of the acenocoumarol, the enzymes had improved. The patient made a full recovery within two months. This case suggests a causal relationship between acenocoumarol exposure and liver damage.