Application of hyaluronan (HA) containing cosmetic products to the skin is reported to moisturize and restore elasticity thereby achieving an antiwrinkle effect. In the skin, HA can be synthesized by dermal fibroblasts and N-acetylglucosamine (NAG) is a precursor for HA biosynthesis in the body. To study the effects of exogenous NAG on HA production in human dermal fibroblasts, HA production and HA-synthesizing enzymes 1, 2 and 3 mRNA expression in cultured human dermal fibroblasts were measured by ELISA and RT-PCR, respectively. The results showed that NAG promoted HA production while had no effect on the expression of HA-synthesizing enzymes 1, 2 and 3 mRNA in human dermal fibroblasts.