Quantitative immunoelectrophoresis used for the analysis of a diaivsed. cemrifuged and trceze-dried extract irom cow hair and dander revealed 17 antigens. Five of these were identified as serum proteins. Partial identity to antigens of serum and extract from hair and dander of goat, sheep, swine, horse, dog, cat and guinea pig, and to antigens of house dust was demonstrated. Sera from 36 patients with manifest allergy to cow hair and dander selected on the basis of case history, RAST, skin and provocation test, were examined in crossed radioimmunoelectrophoresis (CRIE); sera from five persons with high serum IgE, but without allergy to cow hair and dander, and sera from five normal individuals were controls. 31/36 of the sera contained IgE with specific affinity for two of the antigens of the extract. Further, two major and six minor allergens were identified. The control sera showed no specific IgE binding. A significant positive correlation was found between RAST and CRIE for the first group of patients. The approximate molecular weights of the four major allergens obtained by means of gel chromatography were; 2.4 × 104, 2× 104, 2×104 dalton, respectively Using Con-A and Con-A Sepharose in crossed immunoaffinoelectrophoresis, eight of the antigens were revealed to contain groups with affinity for Con-A. [ABSTRACT FROM AUTHOR]