The allergic diseases of the airway, i.e. allergic rhinitis and asthma, are on the increase in Thailand and their prevalence shows no signs of abating. When compared with a previous study, the incidence of wheezing had increased 4 fold (from 4.2% to 18.3%), and allergic rhinitis increased nearly 3 fold (from 17.9% to 44.2%). The results of the ISAAC phase III study revealed that the frequency of allergic diseases of the respiratory tract increased significantly from the ISAAC phase I survey performed in 1995; i.e. asthma increased from 12.2% to 14.5%, and allergic rhinitis from 37.9% to 50.6%. Allergic rhinitis exerts a major impact on the quality of life of Thai patients. The results of skin prick testing have indicated the leading causes of indoor (house-dust mites, house dust, cockroaches, dogs and cats) and outdoor pollen (Bermuda grass, para grass, sedge, careless weed) allergens. Molds (represented by Cladosporium), although prominent in an aeroallergen survey, returned a low percentage of positive skin prick reactions, and therefore, were considered low in allergenicity. In Thailand, there are clinical practice guidelines for both allergic rhinitis and asthma which are comparable to the international guidelines like ARIA and GINA. Sufficient kinds of pharmacotherapy are on the National List of Essential Drugs. Yet due to the limited number of trained allergists, many patients are seen by general physicians, and often, the appropriate diagnostic tests and treatments are not provided. In addition, the financial burden for quality health care may be prohibitive for those without private health insurance in spite of the implementation of a universal health care system for all Thai citizens, which is less than optimal.