In eukaryote cells chromatin is composed of DNA, histone and nonhistone proteins. Among them histone was isolated from chromatin by the replacement with protamine. followed by a gel filtration for the separation of whole histone from the residual protamine. Whole histone was further fractionated to two fractions, A and B. These histone preparations were more native and soluble than that obtained by acid extraction. A DNA-protein complex, nucleosome was prepared by the DNase II digestion of calf thymus chromatin, but perfect digestion to nucleosome monomer could not be carried out. Protein: DNA ratio of this nucleosome (2.07) suggested that nonhistone proteins were also present in nucleosome.