Immunoglobulins G, A, M, D, and E were studied in the sera obtained from sxity-nine bronchial asthma patients, who were graded objectively according to atopic score. Among other associated atopic diseases, they often had allergic rhinitis. Ninety-one per cent of these patients had elevated serum IgE levels and the mean level of serum IgE was more than 3-5 times higher than that observed in the normal subjects. Moreover, as their atopic score increased, the serum IgE levels were also elevated, and every patient with high atopic score, had elevated serum IgE levels. This indicates the association of atopic state with serum IgE level. Furthermore, reaginic antibodies were studied in some of these patients by intradermal tests, Prausnitz-Küstner (PK) reaction, conjunctival and bronchial provocation tests. Intradermal and PK tests were comparable and proved to be the most sensitive method of detecting reagins. The intensity of these reactions correlated significantly with serum IgE LEvel, although this relationship is not invariably present. The reaginic activities in the sera of the patients with atopic bronchial asthma also compared well with the positive bronchial test (induced asthma) by inhalation of specific aerosol although this association is also not always present. Eleven patients with high atopic score had isolated serum IgA deficiency. There was a significant rise of mean serum IgM in comparison to the controls.