We present the second human Y-specific minisatellite, MSY2 (DYS440). It consists of three or four copies of a 99-110bp repeat unit and is located about 1kb upstream of the DBY gene. The most common allele contains four units, but a three-unit allele has arisen on at least four occasions; in chimpanzees and orangutans, MSY2 contains only two units. It is therefore evolving slowly and provides a particularly useful polymorphic marker for Chinese populations.