We developed a highly efficient screening method for minimizing the hybridization of high-density replica (HDR) filters and for allowing simultaneous use of numerous oligonucleotide probes for STS markers. We designated this method "digital hybridization (DH) screening," in which a binary n-bit ID number is given to each probe, and a series of probe mixtures is prepared in an arranged combination. The matrix pattern between probe mixtures and hybridization signals determines the relation between a particular STS marker(s) and the corresponding DNA clone(s). Here, we describe a successful DH screening of over 15,000 human BAC clones with 126 STS marker probes with 7-bit LD numbers, which required only 8 sets of HDR filter hybridizations. Our results indicate that DH screening can be performed with more than 1000 STS marker probes with only 10-bit ID numbers. The DH screening method is convenient, economical, and of high fidelity, and thus it should facilitate the construction of sequence-ready DNA contigs for the human genome as well as for genomes of various species. The principle of DH screening has various applications to the biological sciences. (C) 1998 Academic Press.