Quantitative immunoelectrophoretic methods were used for the analysis of the allergens in cow hair and dander and for comparison with related preparations. The immunoelectrophoretic precipitation pattern of an extract from cow hair and dander showed 17 precipitates. Crossed radioimmunoelectrophoresis showed four of these to be major allergens of the extract, and these allergens are common major allergens in four investigated cow breeds. The allergens are associated predominantly with hair and dander, but they were also demonstrated in cow saliva, urine, whey, amniotic fluid and beef, as well as in cow-hide products. Allergens displaying partial immunological identity with the major allergens of cow hair and dander were found in extracts from goat and sheep pelts, in products made of these materials such as carpet and knitting wool, and in carpets made of animal hair.