A comparison was made of the basic proteins extracted from the chromatin and nuclei of Achlya bisexualis, Blastocladiella emersonii, and Pisum sativum. Extraction of purified chromatin and nuclei of the Chytridiomycete, B. emersonii followed by gel electrophoresis produced no detectable protein bands. Extractions of purified nuclei and chromatin by either mineral acid or CaCl2 from the Oömycete A. bisexualis resulted in several protein bands following separation by disc gel electrophoresis. Monitoring the nucleic acids during the nuclear isolation procedure as well as comparing electropherograms of basic nuclear proteins with basic ribosomal proteins suggests no significant contamination of the nuclear preparations with ribosomes. Carboxymethyl cellulose chromatography of the A. bisexualis nuclear basic proteins resolved three distinct fractions. Gel electrophoresis of the CM cellulose fractions indicated heterogeneity of each fraction. Amino acid analysis of the CM fractions showed that they were all lysine-rich and meet the basisity requirements of histones.