Allergenic components in extracts of Acarus siro and Tyrophagus putrescentiae were identified by sodium dodecyl sulphate-polyacrylamide (SDS-PAGE) and immunoblotting. Five and four allergenic components, respectively, were visualized with sera from farmers sensitized to storage mites. The highest frequency of IgE-binding was to a 15 kDa component of A. siro (7/9 sera) and a 16 kDa component of T. putrescentiae (23/29 sera). The allergenic crossreactivity of A. siro and T. putrescentiae with Lepidoglyphus destructor and Dermatophagoides pteronyssinus was studied with an immunoblotting inhibition technique. Crossreactivity between D. pteronyssinus on the one hand and A. siro and T. putrescentiae on the other, was shown, as the IgE reactivity to a 25 kDa component of D. pteronyssinus was inhibited to the same degree by extracts of A. siro, T. putrescentiae and D. pteronyssinus. However, D. pteronyssinus was a poor inhibitor of the allergenic components of A. siro and T. putrescentiae. Strong cross-reactivity was also shown between L. destructor and the allergenic components of A. siro and T. putrescentiae, while the latter mite species only to a very low degree inhibited the allergenic components of L. destructor.