Background: Skin prick test (SPT) of immediate hypersensitivity is a main instrument in the diagnosis G1, 39% in GII and 65% in GIII (p <0.001). The predominant allergens for each group were dust mites (Dermatophagoides pteronissinus and farinae). Conclusions: SPT was useful when used on a selected pediatric population. The frequency of sensitization increased significantly with age. However, more than one third of children between 2 and 4 years of age tested positive to one or more allergen, demonstrating its applicability in this age group (Rev Méd Chile 2005; 133: 195-201).