Licorice extract is a well known herbal drug. Glycyrrhizin(GL), a kind of saponin, is one of the main active components of licorice extract. The reported effects of GL on the biological system are anti-inflammatory, anti-ulcerous, anti-cariogenic, and anti-viral. In this study, the authors investigated the effects of GL on contact hypersensitivity (CHS) to dinitrofluoro-benzene(DNFB). GL inhibited the elicitation of the CHS only when given between the period of sensitization and ear challenge. By using adoptive transfer experiments, the authors confirmed that GL effects only the efferent phase of the immune responses.