Provocation tests, skin tests, and RAST were performed in 156 asthmatic children, using eleven different allergens (moulds, animal danders, and pollens). A total of 305 positive and 676 negative provocation tests were performed. For positive provocations there was an overall agreement with RAST in 61% of the instances, for negative bronchial tests in 94%. The agreement was found to be allergen dependent. By combining RAST and skin tests, it was possible to arrive at a conclusive allergy diagnosis in a higher number of instances than if either skin testing or RAST was used alone, but in a considerable number of instances provocation tests were found to be necessary to secure the allergy diagnosis. The results obtained with RAST in this study were less favourable than those of other studies, probably because of the use of lower quality allergosorbent material.