Rederivation enables one to decontaminate colonies of laboratory mice and rats from specific pathogens and to convert them to the SPF (specified pathogen free) state. In this study the results of the rederivation of two unique rat strains that were selected at the Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, viz., tame Norway rats, rats with inherited stress-induced arterial hypertension (ISIAH), and the ICR mouse strain, are presented. The SPF state of the rederivated rats was confirmed by indicator animals, which are also called sentinel animals. An optimized rederivation model of laboratory animals is suggested in the article, which includes a series of embryotechnological methods, viz., freezing and cryopreservation of embryos, their decontamination by washing in sterile media, cultivation for 48 h, and, finally, transfer to recipients (with the SPF state). As a result of the application of this model to the ICR strain mice, it was possible to obtain 39 offspring that were born in the conditions of an SPF animal facility. It is worth mentioning that the efficacy of the procedure is in agreement with international standards, with all three lines representing a specific phenotype after undergoing all the procedures of rederivation.