The allergic responses to mite and Candida antigen were analyzed in atopic and non-atopic asthmatics to clarify the mechanisms of severe bronchial asthma. Skin responses and serum level of antigen specific IgE to mite antigen were lower in severe atopic asthmatics, especially in intractable atopic asthmatics. The serum level of antigen specific IgG1 and responses of peripheral blood lymphocytes to mite antigen showed no difference with severity in either type of asthma. Atopic severe asthmatics had higher serum levels of antigen specific IgE antibodies to Candida antigen and higher serum levels of antigen specific IgG1 antibodies to Candida antigen than atopic mild and moderate asthmatics. Non-atopic severe asthmatics had higher serum levels of antigen specific IgG1 antibodies to Candida antigen and higher responses of peripheral blood lymphocyte to Candida antigen than non-atopic mild and moderate asthmatics. In atopic and non-atopic severe asthmatics, bronchial provocation tests by Candida antigen showed higher positive responses than mild and moderate asthmatics. These findings suggest that a common mechanism makes asthma severe in atopic and non-atopic asthma and that Candida antigen plays an important role in both types of asthma.