Morphologic changes in vitro of basophils from the peripheral blood of patients with atopic bronchial asthma (serum IgE more than 1000 u/ml) and intractable bronchial asthma (serum IgE less than 100 u/ml) were studied by addition of anti-IgE or anti-IgG. In supravital observation by differential-inteference microscopy, basophils when exposed to anti-immunoglobulin moved rapidly and changed morphologically to a pear-shape and next to a hand-shape and the granules were degranulated from the tip of the cytoplasmic processus in a manner of exocytosis. In the observation by phase contrast microscopy, intracellular changes of granules and vacuolation were observed clearly, but ejection of granules were not observed by this method.