Radiolabeled 1-naphthyl-beta-D-glucuronide and 1-naphthyl-beta-D-glucoside were synthesized from 1-[14C]naphthol. The fate of the three compounds in male mice was studied. After a po dose of 45 mg/kg of 1-naphthol, 100 mg/kg of 1-naphthyl glucuronide, and 100 mg/kg of 1-naphthyl glucoside, 95, 93, and 81%, respectively, of the administered dose were eliminated 72 hr after treatment. 1-Naphthyl glucoside was eliminated more slowly than the other two compounds. 1-Naphthol was metabolized predominantly to the sulfate and the glucuronide conjugates, whereas a portion of 1-naphthyl glucoside was eliminated directly or cleaved and then reconjugated to form the sulfate and the glucuronide conjugates. 1-Naphthyl glucuronide was excreted as parent compound and sulfate, indicating hydrolysis and resynthesis. When the glucoside was administered at three doses (10, 50, and 100 mg/kg), it was observed that the lower doses of the glucoside were more readily eliminated in the urine than the higher doses. Larger amounts of the parent compound were found in the excreta at the lower doses than at the higher doses.