Objective    To study the growth and development as well as reproductive capacity of CL Long Evans rats.     Methods    Eighty CL Long Evans rats（80 days old）were bred in a barrier system. A monogamous mating system is used to reproduce 5 litters. Their main indexes of growth and reproduction were determined. The body weight gain of 60 second litter rats were analyzed from day 20 to 100.     Results    The number and weight of the fetus

the weaning time weight per cote and per litter in the second litter were the highest

and the fifth litter was the lowest. The growth and development curve was the same as that announced by Taconic.     Conclusion    Long Evans rats have been confirmed suitable for continual reproduction for 4 litters and the second litter is the best one for mating.