OBJECTIVE: To evaluate the efficacy of intravenous cyclophosphamide pulse therapy (IVC) in proliferative lupus nephritis (PLN) with normal serum creatinine. METHODS: We retrospectively reviewed 53 PLN patients treated with IVC more than 6 times from 1992 to 1997. The patients were classified into the alternative and the initial. In the former, IVC was started after failed remission with steroid or steroid and oral immunosuppressive drug; in the latter, IVC was started as initial treatment. Remmission was endpoint of study and defined as all of the followings should be maintained for more than 6 months, 1) 24-hour urine protein less than 1g, 2) normal serum creatinine, 3) less than 5 RBC in high power field microscopy and no granular and RBC cast in urine. We compared remission rate and frequency of complications associated with IVC between the initial and alternative by chi-square test and analyzed the variables of remission including methodological; initial or alternative, clinical; age, onset age of systemic lupus erythematous (SLE) and lupus nephritis (LN), duration of SLE and LN, laboratory; serum concentration of creatinine, C3, C4, albumin, anti ds-DNA Ab. titers and 24 hour urine proteins and pathological; activity and chronicity index, multivariatly. RESULTS: All 53 patients (22 initial, 31 alternative) had normal serum creatinine at start of IVC, treated with 9.7 +/-2.3 times of IVC and followed up during 37.2 +/-15.4 months. Thirty-four patients (64%) had remission (18 of the initial and 16 of the alternative). The remission rate of the initial was higher (82% vs 52%, p=0.04 by chi-square test) than the alternative, but frequency of complications was not different. In multivariate analysis, any other variables; including methodological, clinical, laboratory and pathological, did not influenced on remmission significantly. CONCLUSIONS: IVC is effective in PLN with normal serum creatinine as initial treatments and our results suggest that IVC may be chosen as an alternative therapy in PLN patients who failed remission with steroid or steroid and oral immunosuppressive drug.