The prevalence of allergic disorders has increased markedly throughout the world over the past three decades. It seems probable that the increased prevalence is real because longitudinal studies have shown a rapid exponential increase in allergic disorders. In order to determine the prevalence of type 1 allergy in patients with allergic disorders in Sistan-Blouchestan province, in the Southeast of Iran, patients referred to Immunology and Allergy Medical Center of Khatam Hospital during a 7-year period were studied. One thousand two hundred and eighty-six patients (554 males and 732 females), aged 2-79 years, had allergic disorders. The most frequent allergic disease was rhinitis, seen in 959 patients (74.57%). Also, 939 patients had a history of sinusitis (73.02%). Among the skin prick test(SPT)-positive patients, a positive prick test reaction to the house dust mites (89.74%), feathers (70.29%), and Aspergillus (65.08%) was most common, followed by Alternaria (57.39%), Cladosporium (47.12%), grasses (43.39%), trees (41.29%), Penicillium (39.19%), fruits (38.41%), and weeds (32.50%). Also, 30.33% of the subjects were sensitized to Hen’s egg in the prick test, walnut (29.16%), cow’s milk (21.46%), beef meat (19.21%), and hazel-nut (15.32%) accounting for other positive reactions. The prevalence of SPT-positive to common allergens is high among Iranian patients with allergic disorders. So, it should be recognized in the diagnosis of allergic diseases as well as in allergen-reduction programs.