Ginseng root is an important remedy in oriental countries, which has been used for thousands of years. Saponins of ginseng root has been known to be the major component which mediate diverse pharmacological actions of the ginseng. Heat processing of ginseng root potentiates its biological activity such as anti-tumor and anti-oxidative activities. The butanol fraction of heat-processed ginseng (HGB) induced the production of nitric oxide in macrophages in a dose-dependent manner with IFN-${gamma}$(30 U/ml) priming. The active component was identified as ginsenoside-$Rg_5$ from the activity-guided purification. Ginsenoside $Rg_5$ is one of major components of heat-processed ginseng and red ginseng that is responsible for the potentiated biological activities of processed ginseng. The induction of NO production by heat-processed ginseng might contribute to the potentiated biological activity of heat-processed ginseng.