Two hundreds consecutive asthmatic patients from Taif City, which is 5500 feet above the sea level, were investigated by history and allergic prick skin testing for various inhalant allergens. The highest positivity in the present work was to house dust (65.5% by history and 83.5% by prick skin test). The skin test for house dust mite D. pteronyssinus was 6.5% and for D. farinae was 2%. Skin testing for trees pollens was 73%. So it is evident that, there is a lower prevalence of bronchial asthma associated with positive skin test to house dust mites and higher prevalence of pollen allergy at high altitude due to effect of low relative humidity and temperature at high altitude.