Despite wide therapeutic use of CpG ODN against infection, allergy and cancer, the safety and toxicity of CpG ODNs were poorly delineated. Thus, we investigated whether optimal dosing of CpG ODN would affect immunotoxicological parameters in NZB/NZW F1 mice. Comparisons were made among control, non-CpG ODN and mouse CpG ODN ($10{mu}g$)-treated groups for 4 weeks. To gauge the immunotoxicity of CpG ODNs, we measured nonspecific parameters, degree of lupus nephritis, proteinuria, or autoantibody, and cytokine expression in mRNA level of lymphocytes. We found that there were no significant differences among groups in nonspecific immunotoxicological profiles and in evaluation profiles of glomerulonephritis. However, titer of anti-dsDNA and anti-cardiolipin antibodies in mouse CpG ODN group rose three or eight-fold higher than in control group. Collectively, CpG ODN might be clinically less immunotoxic in terms of clinical profiles in lupus-prone NZB/NZW F1 mice, in spite of high autoantibody titer in CpG ODN treated groups.