RESUMO
We compared in 50 asthmatic children, the cutaneous response by skin prick test to Dermatophagoides farinae with antigens from two different laboratories (Freeman and Hollister). In order to evaluate the importance of the selection, conservation and standardization of the allergic extracts. 27/50 children had a similar response, in those cases (6) where Freeman was doubtful and Hollister positive the allergic etiology was confirmed by RAST and Challenge tests. In 5 cases, Freeman was negative and Hollister doubtful we only confirm allergic etiology in 1. When both were positive all of them were allergic. The antigen Dermatophagoides farinae from Freeman laboratory needs another diagnostic method, when the cutaneous response is doubtful or negative and the clinical feature is highly suggestive. We don't have to forget the importance of the controls positive and negative.