The antioxidative effects of methanol extracts of crude drugs were estimated by an electrochemical method because there are many electrochemically-active substances in natural antioxidants. Twelve kinds of crude drugs, which had been reported to exhibit strong activity in an antioxidative test based on the air oxidation of linoleic acid, were studied. The oxidative capacity calculated from voltammograms of their methanol extracts were compared and examined together with data on their radical scavenging effects. The results showed that the electrochemical behavior in most cases correlated with the radical scavenging effect. Crude drugs which had clear oxidative peaks below + 1.2 V and a large oxidative capacity were suggested to have strong radical scavenging effects. It was clear that substances oxidied at lower potentials had stronger radical scavenging effects than those oxidized at higher potentials. Therefore, this electrochemical method can be considered as a rapid and simple method for estimating the antioxidative effects as a radical scavenger.