We described a 30-year-old pregnant woman developing antinuclear antibodies (ANA)-negative systemic lupus erythematosus (SLE) accompanied with arthritis, malar rash, lymphopenia, autoimmune hemolytic anemia, pericardial and pleural effusion, proteinuria and seizures. All serum autoantibodies except anti-Ro antibody were negative. An artificially induced abortion was performed to prevent SLE deterioration. Steroid and cyclophosphamide therapy were effective for this patient. During the 2-year follow-up period, her ANA and other SLE-related autoantibodies in serum remained negative. This case suggests that ANA may not be required in the pathogenesis of SLE, even in the case with pregnancy, and ANA-negative SLE may also have a dangerous clinical course.