Objective: To measure the expression levels of BLyS and its receptors mRNA in peripheral blood mononuclear cells(PBMC) using real-time fluorescence quantitative polymerase chain reaction(RFQ-PCR) method and to investigate the relationship between BLyS and its receptors mRNA expression and systemic lupus erythematosus (SLE). Methods: Specific primers and TaqMan probe were designed, and RFQ-PCR was performed. According to the standard curve of plasmid DNA, the level of BLyS and its receptors mRNA expression in 23 patients with SLE and 23 healthy subjects were determined. The ratio of the copy number of BLyS mRNA to that of β2-microgluobulin (β2M) mRNA and the ratio of the copy number of BLyS receptors mRNA to that of β2M mRNA were regarded as indicator for the levels of BLyS and BLyS mRNA expression. Results: The concentration of RFQ-PCR was in the range of 10 - 109 pg/ml,and the coefficient of variation values for both intra-experimental and inter-experimental reproducibility ranged from 2.40％ to 10.12％ and from 4.26％ to 12.29％, respectively. In 23 SLE patients, the level of BLyS and its receptors(BCMA, TACI, BAFF-R) mRNA were in the ranges of 1.27～ 1.49, 0.64～0.77, 0.83～ 1.05 and 0.98～ 1.37, respectively. The mean values were 1.38±0.07, 0.70±0.04,0.91 ±0.06 and 1.15±0.12, respectively. In 23 healthy donors, the levels of BLyS and its receptors(BCMA, TACI, BAFF-R) mRNA were: 0.60 ～ 1.0, 0.55 ～ 0.80, 0.54 ～ 0.74 and 0.54 ～ 0.77, respectively. The mean values were 0.83 ± 0.13, 0.68 ± 0.08, 0.65 ±0.07 and 0.68 ± 0.06, respectively. Conclusion: This results suggest that BLyS, TACI and BAFF-R might be involved in the pathogenesis of SLE and the mRNA expression levels might be used as new markers for the diagnosis of SLE.