Studies were made of the peripheral blood pattern, serum immunologic reactions (CRP test, ASLO test, Cold haemoagglutination test, Paul-Bunnell test), erythrocyte sedimentation rate, serum protein, electrophoretic pattern and skin test with allergen extracts in 175 adult patient with bronchial asthma. The patients were divided into the following 3 groups: Swineford's atopic and infectious type groups, as well as a third group called mixed type to designate the boderline cases. They were comparatively studied as to the type, episode and remission. The results obtained were as follows: 1) WBC, ESR and positive CRP rate increased in the infectious and mixed type groups irrespective of asthma attacks. Eosinophile count in the atopic and mixed type groups was higher during the attack than during remission. Allergen extract test, as well as WBC, ESR, CRP and eosinophile count were useful in the diagnose and classification of asthma. 2) RBC, WBC, neutrophile count and Hb-content increased in all three type groups during the attack in comparison with those during remission. It is suggested that the criteria of Swineford for the classification of asthma should be influenced by the presence or absence of asthma attacks.