The urinary metabolites of benzoic acid have been studied in seven marsupial species and the rat. Benzoic acid was excreted mainly as the glycine conjugate, hippuric acid, with smaller, though variable, amounts as benzoyl glucuronide. Thus the overall pattern of metabolism was similar to that found in most other mammals. All species formed significant amounts of a recently discovered metabolite of benzoic acid, 0-hydroxyphenylpropionic acid, suggesting that the metabolic pathway for its formation, involving the addition of a two-carbon fragment, may occur generally in other species.