A method for the paper chromatography of aureomycin is here described.Out of 43 kinds of developing solvents studied, four have been proved satisfactory.They are:(1) n-butanol saturated with M/10 citrate buffer of pH 3.9,(2) 1% aqueous solution of boric acid,(3) M/10 citrate buffer of pH 3.9 saturated with n-butanol, and(4) n-butanol-acetic acid-water(5:1:4).The upward Ra values for the above four solvent systems paper is are 0.40±0.02, 0.83±0.02, 0 and 1 respectively when Whatman No.1 filter used.For general purpose the first solvent is preferred.With this solvent, the RP values for terramycin hydrochloride, streptomycin by drochloride-calcium chloride complex and chloromycetin are 0.32±0.03, 0 and 1 respectively.