This study was carried out to investigate the effect of Glycyrrhizae Radix on serum corticosterone and blood histamine content by immobilization stress in mice. Corticosterone secretion and blood histamine level was significantly increased in mice by subjecting the animals to immobilization stress 1 hr. after intraperitoneal injection of Glycyrrhizae Radix extract (150 mg/kg) and glycyrrhizinic and (15 mg/kg). whereas, administration of cortisol $(7.5;{mu}g/kg)$ provoked a decrease in corticosterone secretion and histamine levels. These results suggested that glycyrrhizinic acid was effective on cortiosterone release provoked by immobilization stress and this release was mediated in part by histamine.