A non-invasive, immunological method for sexing mammalian sperm would be of benefit to agricultural industries. This paper presents a new approach, based on the hypothesis that sex-specific proteins (SSPs) are evolutionarily more highly conserved than non-SSPs. Antibodies to non-SSPs were raised and used in an affinity procedure to remove non-SSPs and enrich for SSPs. Thereafter, using column chromatography, purified SSPs were obtained. Sex-specific antibodies (SSAbs) raised against these SSPs appear to bind to sex-chromosome-specific proteins (SCSPs) on the sperm membrane and make possible a sperm-sexing procedure. Antibodies to SCSPs were raised and used to identify putative SCSPs by affinity chromatography. The preliminary results presented here suggest that a viable immunological sperm sexing procedure can be developed.