OBJECTIVE: To understand the allele structure and reveal genetic polymorphism of Y chromosome specific short tandem repeat (Y-specific STR) loci in Chinese Han population. METHODS: The authors used a set of five Y-specific STR loci which were tetrameric tandem repeat loci chosen from the Genome Database. EDTA-blood specimens were collected from the unrelated individuals. DNA was extracted by Chelex method and amplified by the polymerase chain reaction (PCR). The PCR products were analyzed using both the PAGE horizontal electrophoresis with discontinuous buffer system and the automated fluorescence detection approach. RESULTS: The authors observed that the alleles at the five Y-specific STR loci were composed of some complex repeat structures. They successfully prepared a set of human allele ladders for the typing of the five Y-specific STRs and demonstrated the polymorphisms at the five Y-specific STR loci in Chinese Han population. CONCLUSION: Y-specific STRs are good genetic markers for the purpose of analysis of genetic relationship between populations. This preliminary study not only reveals allele frequencies and haplotype distribution of Y-specific STR in Chinese Han population, but also indicates a reference population for detecting male migration events and for reconstructing paternal history.