It was attempted to observe the physiological role of L-carnosine (β-alanyl-L-histidine), especially wound healing effect in the view of biochemical standpoint. The effect of L-carnosine on the proliferation, the change of collagen production and secretion of rat skin fibroblast (Sprague-Dawley strain, fetal age:18-20 days) was investigated. Proliferation of cultured fibroblast for 24 hours was accelerated to 120-130% in the presence of L-carnosine. The proliferation of fibroblast, which was cultured in fetal calf serum-free medium, was accelerated significantly. It is suggested that the L-carnosine may act as a fibroblast growth factor (F.G.F.) in the process of wound healing. It was found that the L-carnosine exhibited a stimulating effect on the production and secretion of collagen in non-trypsinized fibroblast.