Five known compounds were isolated from a Cornus officinalis 50% ethanol extract (C. officinalis extract) and a hot water extract. We investigated the photochemical and pharmacological active compounds of C. officinalis hot water extract and ethanol extract. We understood that C. officinalis is a medicinal plant with potent free-radical-scavenging activity not only against reactive oxygen species (H(2)O(2), superoxiside anion, hydroxyl radical, etc.) in a narrow sense, but also against many other free radicals (peroxynitrate, peroxyradical). It is estimated that the reduction effect with C. officinalis extract can block oxidative reaction on melanogenesis. Loganin and cornuside, the components in C. officinalis, showed a significant free-radical-scavenging activity and inhibitory effects on melanogenesis. We report to prove the inhibitory effect of UVB-induced pigmentation in C. officinalis extract through its radical scavenging activity.