Purpose: To investigate changes in the production of tissue inhibitor of metalloproteinase type 1 (TIMP-1) by human retinal pigment epithelial (RPE) cells following argon laser exposure.Methods: Human cultured ARPE19 cells were exposed to argon green laser at four different energy levels ranging from 60mW to 360mW. After laser exposure, the culture media were sampled at 0, 24, 72 and 144 hours for TIMP-1 concentration produced by the RPE cells. The levels of TIMP-1 in the cells treated with different laser energy levels were compared with a control group not exposed to laser application.Immunocytochemistry for proliferating cell nuclear antigen (PCNA) was performed to detect any adverse effects on the RPE cells caused by laser exposure.Results: Immediately after laser exposure, the concentration of TIMP- 1 was not detectable. At 24 hours after laser exposure, the concentration of TIMP-1 increased significantly in RPE cells treated with 120mW and 240mW at 24 hours (P=0.006 and P=0.001respectively) compared with control cells. At 72 hours after treatment, RPE cells treated at 120mW, 240mW and 360mW demonstrated significantly increase in TIMP-1production compared with control (P=0.003, P ＜ 0.001 and P ＜ 0.001, respectively).No significant reduction in cell viability was observed following laser application as detected by PCNA expression.Conclusions: Our results demonstrated that early TIMP-1 production by RPE cells in cell cultures was enhanced following laser exposure.