Dwarfism in American Angus was a major cause of concern in the 1970’s. Until recently when several calves from some sire x dam crosses resulted in phenotypically dwarf calves not cases have been observed since then. Six affected calves from 3 sire and 5 dam matings and unrelated normal Angus animals were genotyped for the presence of known mutations, which have been reported in Japanese brown and Australian Dexter cattle. We detected only wild-type alleles in dwarf and phenotypically normal Angus cattle, indicating that known mutations associated with Japanese brown cattle or Dexter dwarfism are not responsible for dwarfism in the American Angus breed. However, this does not preclude the possibility that novel mutations may have arisen in American Angus cattle. In order to begin to identify the causative mutation(s) for dwarfism, a whole genome scan of the affected American Angus pedigree is being pursued.