A new set of rat RI strains consisting of 11 independent strains and 13 of their substrains was established by inbreeding F2 rats between F344/DuCrj and LE/Stm. The strain distribution pattern was examined for 66 microsatellite loci, 8 biochemical genetic markers, 2 histocompatibility loci, and 2 coat color genes. A rat salivary protein gene Spe1 was newly mapped on Chr 1.