The presence of glycoproteins and sugar-binding sites in the nucleus is well ascertained. In order to verify the existence of specific nuclear protein-carbohydrate interactions, oligosaccharides were released from nuclear or non-nuclear glycoproteins by Peptide-N-glycosidase F, labeled by reduction with NaB3H4 and added to whole chicken liver nuclei and to subnuclear insoluble fractions (nucleoli, nuclear matrix and nuclear envelope). The analysis of the binding of the oligosaccharides to the nuclear fractions, performed in the presence or absence of competitor sugars, suggest that some rare oligosaccharides species, present only among the nuclear carbohydrates, are specifically recognized by the nuclear matrix.