Objective To study the influence of isoniazid on lymphocyte factor expression and macrophage function of rats.Methods Healthy male SD rats were randomly divided into three groups,which was treated for one month,three months and withdrawal for one month after treated for three months,and each group was randomly divided into isoniazid group and control group.The isoniazid groups were ig with isoniazid at dose of 120 mg/kg every other day and control groups were fed on normal saline.At the corresponding time points,the level of interleukin-12 (IL-12) and interferon-γ (IFN-γ) was detected with ELISA method,detected serum lysozyme content by agar plate method,and Comori method was used for the detection of acid phosphatase levels in peritoneal fluid.Results At all the time points,levels of IL-12,IFN-γ and lysozyme in isoniazid group were not significantly different compared with control group.There were statistically significant differences in acid phosphatase between isoniazid group and control group after treated for one month (P ＜ 0.05),but the significant differences disappeared at the next two time points.Conclusion Isoniazid of 120 mg/kg may have no obvious influence on the immune function of rat.We don't detect the immune injury.