The effect of caffeic acid on scratching behavior and vascular permeability changes induced by compound 48/80 in ICR mice were investigated. An oral dose of 500 mg/kg of caffeic acid significantly inhibited scratching behavior and vascular permeability induced by compound 48/80. The inhibitory effects of daily administration of lower doses of caffeic acid, 100 and 200 mg/kg, were also investigated; and it was found that 200 mg/kg significantly inhibited compound 48/80-induced scratching behavior after the second week of consecutive administration. The effect of 200 mg/kg of caffeic acid on scratching behavior was observed up to the third week of the treatment. The decrease in histamine content induced by compound 48/80 was significantly antagonized by 200 mg/kg. The findings suggest that caffeic acid may be effective for treating itch and edema in allergic dermatitis.