Typing of single nucleotide polymorphisms (SNPs) has advantages in forensic DNA identification because SNPs are abundant in genomic DNA and are easily detected using an automated high-throughput system. In this study, we examined the effectiveness of an automated multiplex SNPs typing system based on the "Invader assay". Using this system, multiplex SNPs typing is completed in 40 min without any complex procedures. The typing results were confirmed by direct sequencing, and no inconsistencies were detected between the sequencing results and the typing results. The population data of 21 SNPs from 113 Japanese indicates that the matching probability is about 1.3 x 10(-9). In our experiment, all of 21 SNPs were correctly detected from degraded samples from which typing of short tandem repeat markers was difficult.