1. 3-Phenoxy[14C]benzoic acid administered orally to rats (0.76 to > 100 mg/kg) is extensively metabolized and rapidly eliminated mostly via the urine. 2. The major metabolic pathway involves 4'-hydroxylation followed by conjugation of the resulting phenol with sulphate. Only minor amounts of amino acid and glucuronic acid conjugation were observed. 3. 3-Phenoxy[14C]benzoyl glucoside, derived from the metabolism of the acid by corn leaves, was also rapidly absorbed by rats and eliminated as a mixture of metabolites very similar to that derived from 3-phenoxybenzoic acid. It was concluded that the glucoside conjugate was rapidly hydrolysed to the free acid in vivo.