Objective To obtain the basic data of biological parameters of cleaning inbred strain BALB/c mice.Methods\ Routine methods and instruments were used to determine the biological parameters of 2 months old cleaning inbred strain BALB/c mice and immunological parameters of conventional inbred strain BALB/c mice.Results\ Similarities are shown in hematophysiological indices,biochemical indices,avoirdupois,weight of viscera,and index of viscera.Between cleaning BALB/c mice and conventional BALB/c mice,there are significant differences in hematophysiological indices and biochemical indices.On CD4~ /CD8~ indices,there are significant differences between male and female in conventional BALB/c mice,also between cleaning BALB/c mice and conventional BALB/c mice.Conclusion Biological parameters of cleaning inbred strain BALB/c mice are stable,owing to strictly controlled microorganisms and parasites;and some resulting influences on immunological function of mice.