Objective To investigate the expression of RECK(reversion-inducing eysteine-rich protein with kazal motif) in peripheral blood mononuclear cell (PBMC) of systemic lupus erytbematosus (SLE) patients and the relationship between RECK and matrix metalloproteinase-9 (MMP-9) in SLE. Methods PBMC were isolated from 69 SLE patients and 23 healthy donors. The protein and mRNA levels of RECK in PBMC were determined by Western blot and RT-PCR, respectively, and the MMP-9 mRNA level was tested too. After cultured for 24 h with phytohemagglutinin(PHA) stimulation, these levels and the secretion of MMP-9 were observed. Results Compared with healthy donors, RECK protein and mRNA lev-els decreased in SLE patients, and MMP-9 mRNA level increased, and the secretion level of MMP-9 was higher. After PHA stimulation, compared with blank control, the expression of RECK protein and mRNA were lower, but the MMP-9 mRNA level increased and the secretion of MMP-9 increased significantly. The protein levels of RECK were inversely associated with MMP-9 secretion but no association between RECK protein level and MMP-9 mRNA level was found. Conclusion RECK might play an important role in SLE pathogenesis through inhibiting the secretion of MMP-9. Regulation of RECK expression would be prospec-tive in SLE treatment.