We report a modification of a liquid hybridization method that serves as a rapid, sensitive alternative to Southern hybridization for the analysis of polymerase chain reaction (PCR) products. An aliquot of the completed PCR is mixed with an internally nested, end-labeled oligonucleotide probe, and one cycle of PCR is performed. The products are electrophoresed, dried and analyzed by autoradiography. The method is significantly more sensitive than standard Southern hybridization methods, is equally specific, requires as little as 1-10 picograms of probe and results can be obtained in less than an hour. The procedure is equally useful for identifying products in multiplex PCRs or single-stranded PCRs.