The furanochromones khellin and visnagin have been characterised by 1H and 13C mono- and bidimensional NMR spectroscopies. Their strong affinity with DNA was experimentally confirmed by the complete disappearance of the furano-chromones' NMR signals upon additions of DNA. An intermolecular interaction between furanochromones and the thymidyl moieties of DNA, stabilized by the formation of a hydrogen bond between the thymidyl NH hydrogen and the C = O group of khellin or visnagin, is here proposed. This is suggested by the strong donor-acceptor behavior of these two molecular moieties, as pointed out by a selective 1H-13C Overhauser effect study of the khellin-thymidine model system.