In order to increase the discriminating power of DNA analysis in forensic science, we devised a new triplex STR system using three novel STR loci we previously reported, D14S299 (wg1c5), D15S233 (wg1d1), and 9q2h2. We designated this system a CDH triplex system. The CDH triplex system showed a high discriminating power, especially in Caucasians. This system is composed of three STR loci showing only regular tetranucleotide repeat alleles. We easily enlarged the databases mainly of Japanese, using this system, and compared them with those of Caucasian and Chinese. This CDH triplex system therefore appears to be useful for forensic practice.