The purpose of this study was to evaluate the biological response and gene expression of New Zealand White Rabbit anterior cruciate ligament (ACL) fibroblasts for different wave lengths of light-emitting diode (LED) irradiation. In other words, this study was undertaken to evaluate the effects of different wavelengths of LED irradiation on cell growth, expression of extracellular matrix and growth factors, migration, and expression of actin and integrin. Proliferation assay showed that red (630 nm, 9.5 J/cm(2)) and green LED (530 nm, 9.8 J/cm(2)) irradiated cells were more increased than control group but there was no difference between the control group and the blue LED (460 nm, 27 J/cm(2)) irradiated group. Moreover, the expression of insulin-like growth factor, transforming growth factor-beta (TGF-β1), and collagen I were significantly increased in the red and green LED-irradiated group, but the expression of collagen was decreased in the blue LED-irradiated group. The results of staining showed that collagen and TGF-β1 were weaker in the control group and blue LED-irradiated cells, but stronger in the red and green LED-irradiated cells. Also, in the red and green LED-irradiated group, the expression of actin and integrin was not changed compared to the control group, but the expression of actin and integrin was decreased in the blue irradiated group. This study revealed that irradiation with a wavelength of 460 nm (blue LED) is cytotoxic to ACL cells, but irradiation with nontoxic fluencies of 530 (green LED) and 630 nm (red LED) wavelengths induced cell growth in cultured ACL cells.