To investigate the effects of Danshen root and Carthamus tinctorius Extract(DCE) on the collagen synthesis of rat cardiac fibroblasts (CF).Methods:CF of neonatal Sprague-Dawley (SD) rats were isolated by trypsin digestion method and growth-arrested CF were stimulated with 10^-7mol/L AVP in the presence of varying concentrations of DCE(10mg/L,50mg/L,100mg/L and 200mg/L).Collagen synthesis was measured by ³H-proline incorporation.Results:The results showed that:DCE decreased ³H-thymidine incorporation in CF with a concentration dependent manner.³H-thymidine incorporation values of 100mg/L and 200mg/L DCE groups are 502±35.13cpm/2000cells and 408±24.58cpm/2000cells, respectively, which are significantly lower than that of the control (both P<0.01);With the increase of time, ³H-thymidine incorporation of CF decrease gradually, there are obviously negative relevance between ³H-thymidine incorporation and time.Conclusion:The results indicate that DCE decreases CF collagen synthesis.