By the ion exchange column chromatography the dialyzable nucleic acid derivatives in hen and duck egg were separated. In hen egg white they were adenosine, guanosine, xanthine, uric acid, UMP, UDP-sugars, GDP and UDP. The kinds of them in duck egg white, pullet hen egg white (laid by the hens within 2 months after first lay) and old hen egg white (laid by the more than 9 months after first lay) were almost the same. But quantitatively, hen egg white contained about 6-7 times more GDP and about

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... times more UDP than duck egg white. In hen egg yolk and duck egg yolk xanthine and uric acid were detected as dialyzable substances. The acid soluble nucleic acid derivative was UDP-sugars and others were too small in quantity to identify. Therefore it seemed that the extraction by dialysis was more useful than that by acid.