Forty-seven subjects diagnosed as having inhalant allergies to fungi were tested for allergic sensitivity to bakers' yeast. Skin prick tests with yeast extract showed that 35 subjects responded with wheal reactions that were at least 3 mm while 32 subjects were regarded as clearly RAST-positive to bakers' yeast antigens. Skin and RAST testing with purified enolase from bakers' yeast and comparisons with the whole yeast extract showed that the enzyme is a major allergenic component of the extract. This conclusion was supported by results of electroblotting studies. RAST inhibition experiments demonstrated allergenic cross-reactivity between bakers' yeast, bakers' yeast enolase and Candida albicans.