Bronchial provocation tests with allergens are becoming recognized as one of the most important diagnostic parameters for the detection and confirmation of the role of the allergic component directly on the reaction site. Twenty-seven children with positive skin tests and RAST for Dermatophagoides Pteronyssinus were challenged with solutions of the same antigen. Twenty-one (77%) had positive responses expressed by different patterns: Six (28.5%) showed isolated early reaction, seven (33.3%) had biphasic responses. Six (28.5%) showed dual response with prolonged (1-2 hours) late reaction. One child had dual late reaction after 35 hours (ultra-late reaction). Six (28.5%) patients had negative reactions. The results suggest that bronchial provocation tests with antigens performed as outlined in this study can also be applied in the diagnosis of pediatric allergy.