For several years Y-chromosomal microsatellites (short tandem repeats, STRs) have been well established in forensic practice. In this context, the genetic characteristics of the Y chromosome (i.e. its paternal inheritance and lack of recombination) render STRs particularly powerful. However, genetic differences between male populations appear to be larger for Y-STRs than for autosomal STRs, a fact that is most likely due to the higher sensitivity of Y-chromosomal lineages to genetic drift (Forensic Sci Int 118 (2001) 153). The assessment of probabilities for matches between haplotyped male persons or traces/persons requires the typing of a large number of haplotypes in the appropriate reference populations. The haplotype data of a large number of European as well as South and North American populations have been collected and are continuously published online (Y-STR Haplotype Reference Database--YHRD; http://www.ystr.org). The most recent multicentric effort has led to the establishment of an Asian YHRD (http://www.ystr.org/asia) which has been available since January 2002. All databases are maintained and curated at the Institute of Legal Medicine, Humboldt-University, Berlin and will soon be fused to a global repository including populations from all continents.