Objective To investigate the effect of mononuclear macrophage colony-stimulating factor (GMCSF) on the expression of vascular endothelial growth factor (VEGF) in fibroblasts, and explore the role of extracellular signal-regulated kinase (ERK) pathway in this process. Methods GMCSF and/or ERK pathway specific inhibitor (PD98059) were added to the culture fluid of human skin fibroblasts at exponential phase of growth, and blank control group, PD98059 group, GMCSF group and PD98059+GMCSF group were divided. Cells and supernatant were harvested from each group, the expression of VEGF mRNA and protein in human skin fibroblasts of each group were detected by RT-PCR and Western blotting, respectively, and the levels of VEGF protein in the supernatant were determined by ELISA. Results Compared with blank control group and PD98059 group, the expression of VEGF mRNA and protein in human skin fibroblasts and the levels of VEGF protein in the supernatant in GMCSF group were significantly increased (P<0.05), while the parameters in GMCSF+PD98059 group were significantly lower than those in GMCSF group (P<0.05). Conclusion GMCSF can up-regulate the expression of VEGF in human skin fibroblasts, and ERK pathway plays an important role in this process.