Transgenic animals carry a foreign recombinan! gene in their genomes. The first transgenic mice which were produced by pronuclear DNA microinjection for modelling some human diseases have been reported in 1980. However, when the target is especially to use these transgenic animals as protein producing factories and to obtain a recombinant product of transgene in large amounts, all transgenic studies would gain a special point of view this time. The main purpose in this area is to produce recombinant proteins having medical and commercial value in large amounts. In these studies, transgene is expressed in certain tissues such as mammary cells with assistance DNA control elements called promotor. Thus, the targeted recombinant protein can be obtained from the transgenic animal's milk or urine. Under these circumstances, it would be clear that a transgenic mouse's milk amount is not enough for this aim. Because of that, transgenic animals which will be used for producing recombinant proteins in their milk musl be choosen from among the livestocks. In the first step of this technique, in vitro maturation and in vitro fertilization of unmatured oocytes obtained from the ovaries which were recovered from the slaughterhouse were performed. After that, 2 pico litres of gene construct (transgene) in 2-4 ng/ul concentration is transferred into the pronucleus of zygotes. By the sex determination of morula or blastocyst stage embryos, the females are identified to guaranty to get milk yield. The next step is to transfer the female embryos into the foster mosters. Transgenic pups are determined by some molecular techniques such as PCR and Southern Blot. About one lone of recombinant protein is obtained in a year and these proteins much more pure and hygenic than obtained in dead human tissues.