Reactions were determined in 1,606 patients with allergic diseases by specific skin test in vivo, using cigarette smoke as allergen, to study its effects on the diseases. Relationship between positive skin reaction, kinds of allergic diseases, and age and sex of the patients was analyzed with multiple regression. Results showed that proportion of positive skin reaction accounted for 34.5 percent (with 556 cases), and positive skin reaction correlated with the occurrence of allergic diseases, but did not with the age, sex, length of the course of the patients and counts of peripheral white blood cell and eosinophil cell. Airway challenge test with acetylmethylcholine was conducted in 58 patients of bronchial asthma with positive skin reaction. Their forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and peak expiratory flow rate (PEFR) after provocation were lower than those before it. Serum levels of total IgE were determined with ELISA in 223 cases (184 cases with bronchial asthma, 87 allergic rhinitis, and 52 allergic skin diseases) with positive skin reaction, and their serum total IgE level was significantly increased, as compared with the controls.