Almost 10 centuries ago, clinical symptoms of allergy was reported for the first time by the great Iranian scientist, Zakariya Razi. However, his report was neglected because mortal infectious diseases were taken more seriously into account. About 1000 years after Razi, infectious diseases have been dramatically less propagated due to the improvement of hygienic conditions. On the other hand, prevalence of allergic diseases has been increased, causing a great number of people suffering from allergy today. As for allergy diagnosis, patient's history along with the skin prick test by natural extracts are among the oldest diagnostic tools and are still frequently used by physicians. Although natural allergens are used worldwide, the production of standard natural allergen extracts is challenging. Because of the lack of desirable specificity in diagnosing the exact cause of the allergic reactions, natural extract are not considered to be the perfect diagnostic tools. The improvement of molecular biology and biochemical techniques made it possible to identify and purify natural and recombinant allergens. Recent advances made in the field of chip and microarray technology have now allowed one to use microarrayed recombinant allergens for chip-based allergy diagnosis. Based on these advances, this paper reviews the methods for allergy diagnosis and the role of recombinant allergens.