Exploiting a serendipitously observed bovine male-specific signal, generated by the mouse pSP64.2.5EI minisatellite probe, we have cloned a bovine (Bos taurus) Y-specific sequence: btDYZ-1. This sequence is composed of 60 tandem repetitions of a motif consisting of two parts: a 40-bp-long unit, showing a mean divergence of 27% between repeats, separated from the next repeat by a TG-rich stretch varying in length between 12 and 63 bp. The number of copies of this repeated motif has been estimated at 6 X 10(4) per male genome. As a consequence, the corresponding satellite, DYZ-1, might represent approximately 1/20 of the bovine Y chromosome. btDYZ-1 has been mapped by in situ hybridization to the pericentric region of the Y chromosome. It is characterized by a substantial genetic polymorphism and has been shown to be conserved within the Bos and Bison genera of the Bovinae subfamily. This sequence is being used to develop a sexing procedure for bovine preimplantation embryos based on the polymerase chain reaction.