Hong Hua (Carthamus) is a traditional Chinese herb associated with promoting blood circulation and removing Blood Stasis along with relaxation of pre-capillary sphincters in rabbit mesentery. To further understand the effects of Hong Hua on vasomotion of microvasculature at acupoints and its mechanism, the authors measured rat skin microvascular vasomotion using laser Doppler flowmetry at the Pi-shu acupoint, where iontophoresis of Hong Hua extracts was carried out. The authors also determined the in-vitro production of nitric oxide (NO) and endothelin 1 (ET-1) from rat dermal microvascular endothelial cells (DMVECs) treated with Hong Hua extracts. The results indicated that before and after delivery of Hong Hua extracts through iontophoresis, the laser Doppler spectral frequencies were M±SD of 17.5±1.6 cycles per minute (CPM) and 18.6±0.7 CPM, and their amplitudes were 25.4±5.4 PU and 64.7±6.5 PU, respectively. There was a significant difference between the pre-treatment and post-treatment amplitudes (p<0.05). In-vitro experimental results indicated that Hong Hua extracts significantly increased the production of NO and ET-1 from DMVECs, achieving peak concentrations at 6 hours and 24 hours, respectively. These results demonstrated that Hong Hua extracts increased the amplitude of skin microvascular vasomotion at Pi-shu. The authors speculate that the elevation in the production of NO and ET-1 from DMVECs may be one mechanism causing the increase. The findings provide a new perspective for understanding the mechanism of action of Hong Hua on vasomotion features of microvasculature at acupoints and acupoint activation.