Histones F2al extracted from normal and neoplastic cells possess similar amino acid compositions. Tryptic and chymotryptic peptides of the F2al histones have identical chromato-electrophoretic RF values. It is concluded that histones F2al from various sources have similar overall structures. The observed differences in the ratios of ∈-N-monomethyl- and di-∈-N-methyl-lysine in the histones from normal and neoplastic cells may be of significance with respect to gene regulation.