Based on the highly conserved region of human, rabbit and mouse SRY (sex-determining region Y) sequences, primers were designed for the amplification of the unknown homologous sequence of cattle by polymerase chain reaction (PCR). A 200-bp male-specific amplifying fragment was obtained. The fragment shares high homology with the known SRY gene. By using the cloned fragment as a probe to hybridize to the Southern blot of HindIII-digested cattle genomic DNA, a 1.7-kb male-specific fragment was detected, which is considered to contain the 200-bp fragment. When the same pair of primers was used in amplification of human and goat DNA samples, the 200-bp male-specific fragment could be detected.