Abstract: The present invention provides methods and compositions for modifying fertility in a male mammalian subject by contacting the subject's testis cells, germ cells or sperm with a sufficient amount of a composition comprising a ligand that binds, activates, or inhibits activation of, a TAS2R receptor expressed on the cells. Also described are methods for screening a test molecule for its effect on fertility by examining changes in male germ cells, testis cells or sperm resulting from contact with a molecule that binds, activates, or inhibits activation of, a TAS2R receptor expressed on the cells. Compositions for modifying fertility in a mammalian subject, e.g., contraceptive products, include a ligand that binds, inhibits or activates a TAS2R receptor in a pharmaceutically acceptable carrier.