Wang, T., Wang, Z., Cao, J., Dong, Y. and Chen, Y. 2014. Monochromatic light affects the development of chick embryo liver via an anti-oxidation pathway involving melatonin and the melatonin receptor Mel1c. Can. J. Anim. Sci. 94: 391-400. Monochromatic light can influence muscle development during incubation and post-hatching. This process is related to IGF-1, which is primarily secreted by the liver. However, the effect of monochromatic light on liver development of chick embryo is unclear. In this study, 600 Arbor Acres fertile broiler eggs were randomly assigned to four incubators and exposed to continuous red light (R-group), green light (G-group), blue light (B-group), or a dark environment (D-group, control). The liver index of the G-group was higher than that of other groups (6.47-15.46%) at E21, accompanied by a higher percentage of proliferating cell nuclear antigen (PCNA). The superoxide dismutase (T-SOD), glutathione peroxidase (GSH-PX), and total antioxidant capability (T-AOC) contents were the highest in the G-group, and this trend was positively correlated with plasma melatonin (Mel) levels and the Mel receptor Mel1c expression of liver, while the malondialdehyde (MDA) content appeared to follow an opposite trend. In vitro, the administration of exogenous melatonin (250 pg mL^-1) increased the proliferative activity and the antioxidant status of hepatocytes. However, this effect was significantly inhibited by Prazosin, a Mel1c inhibitor. These results suggest that green light improves the antioxidant status of the liver, which is mediated by melatonin and mel1c, and finally accelerates liver development.