The prevalence of peanut allergy in Korea is lower than in America. Peanut extract allergens between the two countries have not been standardized. This study was performed to compare the allergenicity of raw Korean and American peanuts with that of roasted peanuts. We prepared the peanut extracts in Korean raw (KP) and roasted peanuts (KRP), and also in American raw (AP) and roasted (ARP) peanuts. We compared the peanut extract allergens of KP, KRP, AP and ARP in vitro with sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by immunoblotting, T-cell proliferation assay and skin prick test with sera from peanut-allergic patients. SDS-PAGE and Western blotting demonstrated four allergenic extracts, numerous bands that displayed a high prevalence of IgE binding. IgE-binding bands were at 64, 36 and 17 kDa. Western blot inhibition revealed that either KP or AP could almost completely inhibit the reactivity of the other extract. There were no differences between T-cell proliferation assay and skin prick test. In conclusion, this investigation showed no different allergic components in both raw and roast extracts of Korean and American peanuts.