In this study, we investigated in vitro nitric oxide (NO) scavenging effect on nine herbal extracts using an NO donor S-nitroso-N-acetylpenicillamine (SNAP) compared with vitamin C. All herbal extracts effectively reduced the generation of NO radicals in a dose-dependant manner and over 65% in 10h. Especially, Ephedrae herba, Carthami flos and Lonicerae flos declined over 75% of NO scavenging effect, suggested that the herbal extracts are the powerful free radical scavengers and may be effective in clinical applications.