The laboratory rat, Rattus norvegicus, was the first mammalian species domesticated for scientific research, which work dating back to before 1850. From this auspicious beginning, the rat has become the most widely studied experimental animal model for biomedical research (Jacob, 1999). Since the development of the first inbred rat strain by King 1909, over 500 inbred rat strains have been developed for a wide range of biochemical and physiological phenotypes and different disease models (Aitman et al., 2008, Canzian. 1997). In the last decade, there has been an extraordinary increase in rat genomic resources (Gibbs et al., 2004, Pennisi. 2004), and the advent of knock-out technology allow the insertion or deletion of individual genes into the rat by advances in stem-cell technology (Geurts et al., 2009, Izsvak et al., 2010, Tong et al., 2010). Thus, a wide array of research opportunities now open up, especially in studies involving the laboratory rat (Hamra. 2010). However, protocol for sperm cryopreservation and oocytes fertilized in vitro by using cryopreserved sperm are still under development for preservation of most rat strains. Therefore, greater use of the cryopreservation of rat sperm may provide an essential resource to preserve and increase the number of valuable genetic strains for research and application.