On the basis of the research on the relationship between human cytomegalovirus (HCMV) infection and systemic lupus erythematosus (SLE) a study of the effects of HCMV infection on the immunological pathogenesis of SLE was undertaken. Presented in this paper is a brief account of the study. It was found that SLE patients with active HCMV infection had significant higher level of serum interferon-alpha (IFN-alpha) than those without active HCMV infection, but the IFN-alpha induction capacity of peripheral blood mononuclear cells (PBMC) from SLE patients with active HCMV infection was evidently poorer than that from patients without it. There was not any statistically significant difference between the two SLE groups in the IFN-gamma induction capacity of PBMC.