Sera of 11 patients were used to characterize allergens in kiwi fruit, latex, avocado, and banana by SDS-PAGE/immunoblotting and to determine cross-reactions between these allergen extracts in EAST inhibition and immunoblot inhibition. By SDS-PAGE/immunoblotting, allergens with apparent molecular weights of 21, 38, 40, and 42 kDa were visualized in latex extract. In avocado extract, IgE-binding components of 27, 43, 52, 58, 65, 75, and 88 kDa were to be seen, whereas, in banana extract, a 40-kDa protein showed strong IgE binding. Furthermore, allergens of 52, 58, 88, and 94 kDa were detected in the extract of banana. Cross-reactions between these allergen extracts were determined by EAST inhibition. Immunoblot inhibition demonstrated that almost all IgE-reactive bands in nitrocellulose-blotted latex, avocado, and banana extracts and two components of 43 and 67 kDa in kiwi fruit shared common IgE epitopes.