For the purpose of isolation and quantitative estimation of the hydrolysis products of FAD, ion exchange column chromatography was used. The hydrolysates were fractionated stepwise from Dowex-1 (Cl^-) with two systems of combined solvents : (1) Water, 0.002N hydrochloric acid, and 0.01N hydrochloric acid+0.04N ammonium chloride, and (2) 0.1N ammonium chloride and 0.1N ammonium chloride+0.01N hydrochloric acid. The former solvent system could effectively separate FR, AMP, FMP with FAD, and cyFMP, and the latter AMP, FMP with cyFMP, and FAD. The combined use of these two solvent systems was shown to effect clear-cut separation of the flavin nucleotides and adenine nucleotide contained in the hydrolysate of FAD.