Objective:To investigate the role of cyclic mechanical stretch on IL-1β-induced MMPs mRNA expression in synovioblasts of human knee joints  Methods:The fourth-generation synovioblasts of human knee joints were seeded onto type Ⅰ collagen-coated BioFlex 6-well culture plate at density of 4×10,5,/well, the following three different treatment groups were devised:normal group (untreated with IL-1β or cycle stretch), control group (treated with 10ng/ml IL-1β only), stretch group (treated with 10ng/ml IL-1β and subjected to cyclic mechanical stretch at a magnitude of 0-12%, frequency of 1Hz, and time of 60 min per day). After being stretched for 3 days by Flexcell-5000 tension system, RNA was extracted and RT-PCR was performed to detect the MMP1/3/13 mRNA level  Results:Compared with the blank group, expressions of MMP1/3/13 mRNA in the control group were significantly increased (P,<,0.05); compared with the control group, expressions of MMP1/13 mRNA in the stretch group were decreased markedly (P,<,0.05), while he descend range of MMP3 mRNA was not obviously (P,>,0.05)  Conclusion:Cyclic mechanical stretch (at a magnitude of 0-12%, frequency of 1Hz, and time of 60 min per day) may inhibit the MMP1/13 mRNA expression in synovioblasts of human knee joints, which may have the potential to protect cartilage damage induced by synovial inflammation.