The effect of ligustrazine and 764-3 on type I and type II collagen mRNA expression in cultured fibroblasts was studied. The results showed that ligustrazine at a final concentration of 30 micrograms/ml for 24 hours could inhibit type I and type II collagen mRNA expression, 764-3 at a final concentration of 15 micrograms/ml for 24 hours could stimulate type I collagen mRNA expression, but exerted no effect on type II collagen expression. The possible mechanism of 764-3 action was discussed.