Abstract: ObjectiveTo study the influence of chlorella on the immune system of healthy mice.Methods60 BALB/c mice were selected and divided randomly into four groups.Different doses of chlorella pyrenoidosa0,0.15,1.50,4.50g/(kg·bw)were administered to the mice orally for 30 days.A series of classical tests were adopted to evaluate the effects.ResultsThe weight gain of the mice administered with chlorella pyrenoidosa was higher than that of the control,and the difference has statistical significance(P<0.05).The ratio of spleen/body weight,delayed hypersensitivity response,the lymphocyte transformation of mice induced by conA,the phagocytotic ability of macrophages,NK cell activity were all higher than those of the control and had statistically significant differences(P<0.05).The ratio of thymus gland/body weight,the number of antibody-producing cells,the amount of hemolytic antibody and the phagocytotic ability of macrophages for chicken erythrocytes were higher than those of the control,too.But there was no statistically significant difference(P<0.05).ConclusionChlorella pyrenoidosa with disintegrated cell wall can modulate the immune system of healthy mice.