Peanuts are one of the most allergenic foods, and peanut proteins are known to cause the allergic reactions. High oleic peanuts have been associated with the greatly enhanced shelf-life, decreased rancidity of roasted peanuts, a preventive effect against hyperlipidemia, and suppressed lung tumorigenesis induced chemically in mice. In this study, 33 raw peanuts of different varieties purchased from various parts of the world were evaluated and compared with two high- -oleic peanuts (SunOleic, Florunner 458) in allergenicity. Identification of peanut allergens from defatted extracts was accomplished by means of sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) and by using Western immuno-blotting with sera from peanut-allergic patients. The content of oleic acid was also determined and compared to other fatty acids by using gas chromatography (GC) in order to indicate peanut oil quality. SDS-PAGE revealed that the major peanut allergens known as Ara h 1 (64 kDa), Ara h 2 doublet (17 and 19 kDa), and Ara h 3 fragment (14 kDa) were displayed in all protein extracts. In contrast, only low-oleic peanut (LO) varieties contained the protein band at 36 kDa (Ara h 3/Ara h 4) that did not appear in high-oleic and several normal oleic (NO) varieties. The sensitivity to a 14 kDa protein was found to be higher in one patient than another by using immunoblotting. A substantially increased threshold of sensitivity to high oleic peanuts at least 5 times higher than to other peanuts was confirmed by an oral food challenge test, and thus could provide decreased allergenic sensitization.