OBJECTIVE: To examine the efficacy of Korean red ginseng for improving blood flow in healthy people. METHODS: Participants were randomized and treated with 1500 mg of Korean red ginseng extract or placebo for 8 weeks. The effect of Korean red ginseng was evaluated by digital infrared thermal images, and Doppler sonography, and blood test. RESULTS: Forty subjects completed the protocol. Imbalance in local thermal distribution was significantly decreased in the Korean red ginseng group confirmed by digital infrared thermal images. Doppler sonography showed no significant change in maximum and average rates of bloodcirculation in single or complex areas. Blood analyses for coagulation and lipid metabolism factors revealed no significant changes. No abnormal reactions to the Korean red ginseng were observed. CONCLUSION: Digital infrared thermal imaging showed that the temperature deviation in the whole body decreased safely in the Korean red ginseng group, which mitigated the body-temperature imbalance. This result suggests that the Korean red ginseng improves blood circulation in the human body.