We have developed a simple and economical method for HLA-DNA typing, called microtiter plate hybridization (PCR-MPH), which could replace standard PCR-SSO. This method is similar to that of an ELISA. Briefly, the PCR products labeled at the 5' termini with biotin were hybridized with probes immobilized on a microtiter well, and the bound PCR products were detected by streptavidin-conjugated enzymes followed by color development. A system for HLA-DRB1 "generic" typing (e.g., DR1, DR2), using microtiter wells coated with 12 different SSOs has been established. The HLA-DRB types classified using this method agreed well with those obtained by conventional serologic typing. The advantages of this microtiter plate-hybridization method for routine HLA-DNA typing are a short assay time, easy processing of large numbers of samples, and the potential for automation.