It is known that in the reproductive systems, aged-related changes are prominent. Similarly, in normal nonhuman primates and other mammals such as rats, various sexual activities of male and female decline with aging. The purpose of the present study was to clarify the pattern of sexual behavior in matured mice, voles, Syrian hamsters, rats, guinea pigs, rabbits and house musk shrews of both sexes, and to select the appropriate animals for studies of aged-related changes in sexual behavior. There were species differences among laboratory animals in the pattern of sexual behavior. In summary, hamsters and rats ejaculated about three times during 30 min, while mice did once during 10 hrs. The former animals showed the intromission and ejaculation within a few min and 10 min, respectively, the latter did the ejaculation a few hrs after introduction of a heat female. In female animals, rats displayed receptive and proceptive behaviors, while hamsters and guinea pigs did only receptive behavior. From the above results, rats of both sexes may be recommended for studies of aged-related changes in sexual behavior.