Abstract: Since the elucidation of the role of IgE, antibody in the pathogenesis of allergic asthma, a new speculation has been put forward that drugs selectively inhibiting the activity of certain type of lymphocytes relating to the production of IgE will be found some day, and such drugs should afford possibility to a better control of asthma.Along this line, a preliminary study on the immuno-pharmacology of a Chinese anti-asthmatic herb, flores Gonatanthus pumilus (FGP), was carried out. Rats and mice were sensitized with an injection of the plant protein extracted from radix Trichosanthes kirilowii, using aluminum hydroxide as adjuvant, to raise their serum IgE antibody ntent. Relative IgE titres were assayed with the rat PCA method. It was found that the aqueous extract of FGP given orally for four successive daily doses during the 7th-10th post-immunization days markedly decreased serum IgE antibody activity, which was accompanied by a reduction in specific antibody activity in the lungtissue. Such immuno-suppressive effect of FGP on IgE antibody response was also shown in adrenalectomized immunized rats. On the contrary, when inbred C₅₇B1 mice were immunized with minute amount of the same allergen, FGP exhibited a marked increase of IgE, antibody activity, being 4-6 times as that of the control group. At the same time, an enhancement of IgE antibody response was also shown in C₅₇B1 mice spleen cells. FGP exerted little influence on secondary IgE antibody response in CFW mice. It moderately inhibited both serum and spleen cell immuno-hemolytic reactions in Swiss mice but exerted no significant influence on serum hemagglutinin titre and graft versus host reaction. Neither marked direct bronchodilating activity in the gulnea-pig, nor antiallergic effect, as measured by the direct rat PCA method, was observed. In addition, the influences of FGP on the cAMP content in mice thymus and spleen tissue were also reported.