Abstract: Objective To assess the efficacy of low-dose intravenous cyclophosphmide (IV CTX) in treatmerit of old patients with systemic lupus erythematosus(SLE).Methods Twenty-three old patients with newly diagnosed, untreated SLE were included.Patients received 3 times fortnightly IV CTX pulses at a fixed dose of 400mg followed by 3 monthly pulses.All patients were orally administered 0.8mg/kg of prednisone.The changes of the indexes were observed before and after 12 weeks treatment including the scores of SLE disease activity index(SLEDAI) and the levels of C3, C4 ,24-hour urinary protein and anti-dsDNA antibody.Results Among 23 patients, 19 were followed up to 24 weeks, SLEDAI 4 weeks after treatment were all significantly lower than those before the treatment (P <0.01).At week 8, SLEDAI continued to decrease(P <0.05).At week 4,the level of urine protein, the levels of complements C3 and C4 and ds-DNA decreased significantly compared with that before the treatment (P <0.05).Conclusion Intensive low-dose CTX plus prednisone was effective in newly diagnosed, untreated old patients with SLE, and could reduce adverse effect.