SEVERAL attempts have been made to prepare transfer ribonucleic acids, and the purification of alanine1, serine2, tyrosine3 and phenylalanine tRNAs4 by countercurrent distribution methods have been successful. These tRNAs had, in the solvent systems used for countercurrent distribution, the lowest or highest partition coefficients, and this made their isolation possible by countercurrent distribution alone. Other tRNAs do not have this advantage and when isolated by countercurrent distribution are always contaminated with tRNAs of similar partition coefficients. To purify them it is necessary to use column chromatography in addition to the countercurrent distribution technique. This report describes the results obtained in the purification of arginine tRNA III from brewer's yeast by the combination of fractionation methods based on different principles: countercurrent distribution followed by two column chromatographie procedures, one on DEAE-cellulose and the other on hydroxyapatite.