The study reports a case of "pure" tomato allergy in an adult female. The responsible allergen was partially characterized by immunoblot analysis, pepsin digestion, and heating. It had a molecular weight of about 9 kDa and was heat-labile and pepsin-resistant, thus confirming the clinical history. Unfortunately, due to the failure of both 2-dimensional electrophoresis analysis and N-terminal sequencing experiments, it was not possible to characterize the protein further. Based on a comparison with currently known tomato allergens, this seems to be a novel allergen protein.