Lipid transfer protein (LTP) has been reported as an important allergen inducing severe systemic reactions in allergic subjects. The aim of the present study was to estimate the role of LTP in diagnosis of apple allergy in children allergic to birch pollen. The prospective study was carried out on a group of 21 children sensitized to birch pollen and apple allergens, confirmed by presence of specific IgE in the sera of patients. Allergens separated by electrophoresis were probed by Western blotting using hypersensitive patients' sera. Food hypersensitivity to apple was verified by oral food challenge test. Six patients' sera were hypersensitive to birch pollen and apple proteins. Almost all sera recognized specifically the main allergen of apple peal Mal d 3 with molecular weight <10kDa (LTP). Positive oral challenge to apple was found in 52.4% of investigated children. Children allergic to Mal d 1 presented different clinical symptoms. Sensitization to Mal d 3 is very common in children with apple allergy. No correlation between clinical symptoms and sensitization to recombinant apple allergens has been found, LTP may be useful in diagnosis of apple allergy.