Thiamine anhydride which was obtained by reacting thiamine with benzene sulfonyl chloride in alkaline medium was orally administered to some albino rats. The urine excreted was collected and treated with Amberlite IR-50 (H^+ from), from which the metabolite was eluted with NaOH solution. The metabolite thus obtained was identified with 2-methyl-4-amino-5-aminomethylpyrimidine (I) by paper chromatography. Furthermore the urine excreted from the rabbits to whom thiamine anhyride was orally administered was treated with same procedure and the metabolite was obtained as the picrate. From the results of analysis and IR spectra of the picrate, the metabolite in urine in the oral administration of thiamine anhydride was proved to be I.