Exposure to mites other than Dermatophagoides spp., particularly Blomia tropicalis and Euroglyphus maynei, has been increasingly recognized as a cause of asthma. Positive skin tests and serum IgE antibodies to B. tropicalis have been reported in asthmatic patients from several areas of the world, including São Paulo (Brazil), Hong Kong and Tampa (Florida, USA). Analysis of B. tropicalis extracts showed undetectable levels of the major Group I and Group II Dermatophagoides spp. allergens. Immunoabsorption experiments showed that most of the IgE antibodies to B. tropicalis (approximately 70%) reacted with species-specific allergens. Murine monoclonal antibodies to B. tropicalis could present antigens that were recognized by human IgG antibodies. Sensitization to E. maynei has been reported in Europe, North and South America and Australia. Analysis of four different E. maynei extracts by ELISA and RIA showed that E. maynei produces an allergen that is antigenically related to Dermatophagoides Group I allergens. The amino acid sequence of this allergen (Eur m I) has recently been reported. Further identification and purification of B. tropicalis and E. maynei allergens is required to develop specific assays for measuring these allergens in dust samples. This will make it possible to investigate the relationship between exposure to B. tropicalis or E. maynei and the development of sensitization and allergic disease.