Abstract The nucleosome DNA repeat length of chromatin from Saprolegnia ferax was compared to that of the related Oo¨mycete Achlya ambisexualis and to DNA repeat lengths of chromatin from rat kidney and rat cerebral cortex neurons. The repeat length for Saprolegnia was 167 base pairs, consistent with reports of unusually short DNA repeat lengths in fungal chromatins. The acid-soluble nuclear proteins of Saprolegnia were compared to those of Achlya and to histones from the higher plant rye and from rabbit kidney. Both Oo¨mycetes contained acid-soluble nuclear proteins with electrophoretic mobilities identical to those of mammalian and higher plant histones H3 and H4. Also, both fungi contained a prominent unique band designated α, not seen in either the mammalian or plant preparations. Protein α has not been reported in other fungi; however, its presence in both Achlya and Saprolegnia suggests it is an important nuclear protein in the Oo¨mycetes.