The nuclear residual proteins of rat liver have been solubilked by treatment with sodium deoxycholate and separated into four major fractions. These residual proteins are acidic, highly heterogeneous, and contain different amounts of ribonucleic and deoxyribonucleic acid. Their amino acid compositions show that these are distinctly different protein fractions. Furthermore, these residual acidic proteins form complexes with histones to various degrees. The possible significance of these characteristics is discussed.