Objectives. When routine medical management of allergies is inadequate, diagnostic testing by the UniCAPR system or the skin prick test is often recommended to characterize the nature of the symptoms and to provide more specific therapies directed toward the identified sensitivities. The allergen-arrayed chip, which is based on a microarray technique, is a new method for detecting allergen-specific immunoglobulin (Ig) E. The aim of this study was to evaluate the efficacy of allergen-arrayed chips. Methods. A robotic microarrayer made the allergen-arrayed chips by spotting allergen extracts on poly-L-lysine microscopic glass slides. We enrolled 30 patients (19 men and 11 women) with asthma, allergic rhinitis or atopic dermatitis in this study. The serum specimens of allergic patients were tested by allergen-arrayed chips and the UniCAPR system for Dermatophagoides pteronyssinus (Dp), cockroach, egg white, milk, and shrimp allergens. The results were compared to assess the correlation, sensitivity and specificity. Results. The correlation coefficients between allergen-arrayed chips and the UniCAPR system for Dp, cockroach, egg white, milk, and shrimp were 0.92, 0.60, 0.63, 0.51, and 0.57, respectively. The allergen-arrayed chips showed high sensitivity (95%, 100%, 100%, 100%, and 83%, respectively) and specificity (100%, 83%, 86%, 97%, 83%, respectively) compared with the UniCAPR system. Conclusions. Clinically, the information provided by allergen-arrayed chips seems to be similar to that provided by the UniCAPR system. Moreover, the allergen-arrayed chips allow for the determination and monitoring of large numbers of disease-eliciting allergens by single tests and with minute amounts of sera. ( Mid Taiwan J Med 2004;9:96-102 )