The fate of [l4C] dichlorophen (2,2'-dihydroxy-5,5'-dichlorodiphenyl [l4C]methane) has been studied in the rat. The compound was well absorbed after oral examination, with 78% of the dose excreted in the urine and 15% in the faeces in 2 days. The metabolism of dichlorophen involves both sulphate and glucuronic acid conjugation, and a small amount of unchanged drug is excreted. Studies in bile duct-cannulated rats indicated the occurrence of an extensive enterohepatic circulation of dichlorophen monoglucuronide.