In this clinical research, 33 cases of Yin-Deficiency Liver and Lung Heat type extrinsic bronchial asthmatics most commonly often found in Taiwan were studied during the symptom-reducing period. Twenty-tbreeexperimental cases were given Yang-Yin-Ke-Min-Fang (養陰克敏方) in order to modu- late their Yin-Deficiency constitution while the control, 10 cases, took placebo. Three months later, the symptom scores, medication scores and peak expiratory flow rate were evaluated. At the same time, the immunological changes were also observed. The pharmacia CAP PAST FEIA method was used to measure the five.allergen-specific lgE change in serum before and after treatment, and the enzyme- linked immunosorbent assay (ELISA) was used to examine the production of interleukin-2 in lympho- cyte andhistamipein neutrophil in vitro. And the findings are: Aftel'takmgYang-Yin-Kt@Mm-Fang the symptom leores, medication scores,Dermatophagoidespteronysinus-specificlgE,Dennatophagoides farinae-specific IgE and Dermatophagoides microceras-spedficlgE. concentration in experiment group were markedly lower that of the control group (p < 0.05, p < 0.05, p < 0.05, p < 0.01, p < 0.05 respec- tively). As to the total serum IgE, House dust-specific IgE, Blatella gennanica-specific IgE, there was no statisitical difference between the two groups. The production of Phytohemagglutinin-induced inter- leukin-2(IL-2) in lymphocyte singnificantly decreased in experiment group compared with control group (R< 0.05), and the production ofhistamine in neutrophil shows no difference. The conclusion is that Yang-Yin-Ke-Min-Fang can decrease asthmatic symptoms, medication dose and inhibit the formation of allergen-specific lgE and inhibit activated T-lymphocyte to produce IL-2 in the asthmatics of Ying-Deficiency body quality. The precise mechanism of action of Yang-Yin-Ke-Min- Fang in asthma remains to be elucidated.