The preparation of a fluorescent DNA probe based on the derivatization of the terminal hydroxyl group of the sugar moiety of a DNA primer and its applicability to the DNA hybridization assay are described. M13mp8 plasmid primer reacts with 2-(5-chlorocarbonyl-2-oxazolyl)-5,6-methylenedioxybenzofu ran in the presence of sodium azide to form the corresponding fluorescent probe, which can be used for the hybridization assay to the target DNA, M13mp8 plasmid vector. The detection limit of the DNA with the naked eye is 10 ng (approximately 300 fmol)/spot on filters for the hybridization assay.