The pathomechanism of the bronchospastic reaction is not fully explained. Ovalbumin induced bronchospastic reaction in guinea pigs is widely accepted as a classical experimental model and was appleid in this study. The bronchoconstriction, bronchial hypersensitivity and humoral immune response were measured after bronchial infection and chemical injury by formalin vapours. The intensity of the bronchospasm was measured by Lundberg index, the haemolytic activity of complement and the level of circulating immune complexes were measured at the beginning and at the end of the experiment. The increase of the bronchospastic reaction and bronchial hypersensitivity was observed bacterial infection and after formalin vapours too. Bronchial infection and chemical irritation of bronchial tree lead to the increase of the circulating immune complexes level and to the decrease of the haemolytic activity of the complement.