The biotin-modified deoxyuridine 5'-triphosphates are widely used for a variety of non-radioactive DNA labeling reactions including nick translation, random prime labeling, cDNA labeling and 3’-end labeling. The biotinylated probes have been shown to hybridize to homologous nucleic acid at the same rate and to the same extent as non-biotinylated probes. The hybridized biotinylated DNA probes can be detected by avidin and streptavidin. Biotin-20-dUTP can be enzymatically incorporated into DNA via nick-translation, random priming, 3'-end terminal labeling or in the process of PCR. Bio-20-dUTP is used to produce biotinylated DNA probes in a variety of hybridization applications including Southern blots, Northern blots, dot blots, fixed cells and tissues.