Objective To investigate retrospectively the efficacy of cyclosporine A (CsA) in the treatment of membranous lupus nephropathy (MLN).Methods Twenty-four patients with systemic lupus erythematosus (SLE) and biopsy-proven MLN were treated with CsA in combination with prednisone. CsA was given at a starting dosage of 5 mg·kg -1·d -1 for 3 months, with a 1mg·kg -1·d -1 reduction every month and then maintained at a dosage of 2 mg·kg -1·d -1. The dosage of oral prednisone differed from person to person according to levels of extra-renal activity. Clinical efficacy and adverse reactions were retrospectively analyzed. Complete remission was defined as having a urinary proteinuria level (Upr) of <0.4 g/d, and normal serum albumin and serum creatinine (SCr) levels, without SLE activity. Partial remission was defined as having a UPr decrement >50% of baseline value and a serum albumin value of 30-35 g/L, without SLE activity. No response was defined as having a Upr decrement <50% of baseline value and >2.0 g/d, or as a deterioration of renal function, or as having active SLE. Results One patient could no longer undergo follow-up, and the other 23 patients were treated with CsA and followed up for 6-36 months (mean 16.8±8.4 months). The mean starting dosage of CsA was 4.7±0.5) mg·kg -1·d -1 and the trough level of the whole blood CsA was 248±110) μg/L. Twelve patients (52.2%) achieved complete remission, 10 patients (43.3%) achieved partial remission after CsA treatment, and one patient showed no response. At different CsA treatment timepoint, the complete remission rates were 17.4% (3rd month), 21.7% (6th month), 40% (12thmonth), 88.9% (18th month) and 100% (24th month) respectively. SCr elevation, when within a normal limit was not observed in most patients during early CsA administration, and at the end of the follow-up all the patients had a normal SCr. Relapse occurred in 33.3% of the patients after withdrawing CsA for 4-24 months. No chronic CsA renal toxicity was observed in 4 patients who had a repeat renal biopsy after CsA treatment for 6-24 months. Conclusions CsA could be regarded as an effective therapy for patients with membranous lupus nephropathy, but its adverse effects, especially its nephrotoxicity, should be carefully monitored during CsA treatment. Objective To investigate retrospectively the efficacy of cyclosporine A (CsA) in the treatment of membranous lupus nephropathy (MLN). Methods Twenty-four patients with systemic lupus erythematosus (SLE) and biopsy-proven MLN were treated with CsA in combination with prednisone. CsA was given at a starting dosage of 5 mg · kg -1 · d -1 for 3 months with a 1 mg · kg -1 · d -1 reduction every month and then maintained at a dosage of 2 mg · kg -1 · d -1. The dosage of oral prednisone differed from person to person according to levels of extra-renal activity. Clinical efficacy and adverse reactions were retrospectively analyzed. Complete remission was defined as having urinary proteinuria level (Upr) of <0.4 g / d , and normal serum albumin and serum creatinine (SCr) levels, without SLE activity. Partial remission was defined as having UPr decrement> 50% of baseline value and a serum albumin value of 30-35 g / L, without SLE activity. No response was defined as having a Upr dec rement <50% of baseline value and> 2.0 g / d, or as a deterioration of renal function, or as having active SLE. One patient could no longer undergo- up, and the other 23 patients were treated with CsA followed up for 6-36 months (mean 16.8 ± 8.4 months). The mean starting dosage of CsA was 4.7 ± 0.5) mg · kg -1 · d -1 and the trough level of the whole blood CsA was 248 ± 110) μg / At least CsA treatment timepoint, the complete remission rates were 17.4% (3rd month) SCr elevation, when within a normal limit was not observed in most patients early early CsA administration, and at the 21.7% (6th month), 40% (12th month), 88.9% (18th month) and 100% (24th month) respectively. end of the follow-up all the patients had a normal SCr. Relapse occurred in 33.3% of the patients after withdrawing CsA for 4-24 months No chronicCsA renal toxicity was observed in 4 patients who had a repeat renal biopsy after CsA treatment for 6-24 months. Conclusions CsA could be ide as an effective therapy for patients with membranous lupus nephropathy, but its adverse effects, especially its nephrotoxicity, should be Carefully monitored during CsA treatment.