Objective:To investigate the effect of tissue inhibitor of metalloproteinase-1(TIMP-1) on the apoptosis of β cell induced by hydrogen peroxide and the mechanism of TIMP-1 action. Methods:The insulin-producing rat cell line RINm5F cells were cultured and stimulated by H2O2 with or without the addition of TIMP-1(50 μg/L). Cell viability,Caspase-3 and superoxide dismutase(SOD) activity were determined after the cells were exposed to H2O2 and TIMP-1. Results:Cell viability was decreased obviously in RINm5F cells after incubation with H2O2(0.1 mmol/L) for 1 hour alone. In the cells after treatment with TIMP-1(50 μg/L) for 1 hour prior to H2O2,cell viability and SOD activity were remarkably increased and the activity of Caspase-3 was lower significantly than that in the cells treated by H2O2 alone(P < 0.05). Conclusion:TIMP-1 can protect RINm5F cells from apoptosis induced by hydrogen peroxide,which possibly involves in raising the activity of SOD.