Wound healing is a complex process, with various intracellular molecules and cytokines involved. Chymase is a chymotrypsin-like serine protease originally found to be a mast cell protease. In this study, to further investigate the role of chymase in the process of wound healing, the effects of chymase on cell proliferation and cytokine activation in human skin fibroblasts were determined. To determine cell proliferation, MTT assay was employed. The cells were harvested and total proteins were extracted and detected by western blotting. It was found that in vitro cell treatments with chymase led to dose-dependent increases of skin fibroblast proliferation. Moreover, the treatment of cells with chymase for 6 h induced dose-dependent increases in the expression levels of transforming growth factor (TGF)-β1 and interleukin (IL)-1β, although higher doses (120 ng/ml for TGF-β1; 60 and 120 ng/ml for IL-1β) did not facilitate the detected cytokine expression. In addition, treatment for longer periods of time (12 or 24 h) did not increase TGF-β1 or IL-1β expression. The results from our study will strongly facilitate the understanding of the roles of chymase in the process of wound healing.