Objective TW mouse is a new domestic inbred strain,established by the Tianjin Center for Disease Control and Prevention.The aim of the present study was to carry out genetic characterization and detect rare genes in these inbred mice.Methods 25 alleles,including Akp-1 and others,were assayed in the inbred mice by genetic biochemical labeling technique using a homemade biochemical label detection Kit.Results Rare genes were detected at 8 biochemical loci: Amy1,Es2,Es3,Es10,Gpd1,Hbb,Np1 and Pgm2 in the TW mice.Conclusions Polymorphism of DNA sequences in the mice can be detected by biochemical polymorphism analysis with allele isomorphic enzymes.It may be of great importance to provide abundant animal gene bank to serve the identification of disease genes in humans and as an invaluable resource for experimental animal research as well.