Embryo micromanipulation techniques and their potential genetic impact in dairy cattle are discussed. In addition, some aspects of gene transfer are mentioned. Only the technique of splitting bovine embryos and the subsequent transfer of half-embryos has reached a stage which might make its application to cattle breeding possible. However, the main use of identical twins produced by micromanipulation is expected to lie in genetic research. A better understanding of the interaction of maternal effects and genetic effects may influence genetic theories and subsequently animal breeding plans. Identical pairs of young bulls would allow characteristics to be evaluated by means which are incompatible with the later use of the bulls for breeding.