Mite infestation of stored products is a serious threat to food safety and public health. These stored product mites are not only serious pests of stored food but also cause allergies in humans. Thirty serum samples from patients living in suburban areas of Upper Silesia (South Poland) were tested for sensitization to two species of storage mites: Lepidoglyphus destructor [LD] and Tyrophagus putrescentiae [TP]. Patient antibodies against particular antigens were identified using anti-human anti-IgE monoclonal antibodies. Fifteen protein fractions from LD gave positive reactions with IgE antibodies and 18 from TP. Seven of the 30 samples showed positive reactions to a protein fraction measuring about 29 kDa from LD and six reacted with a fraction measuring about 25 kDa from TP. These findings may imply the existence of many protein fractions with allergenic properties besides the characterized allergens in the two tested species.