The house-dust mites, Dermatophagoides farinae, D. pheronyssinus and Euroglyphus maynei are cosmopolitan inhabitants of the homes of humans worldwide. These mites are the sources of multiple potent allergens that trigger allergic reactions in house-dust-mite-sensitive individuals. Many laboratories using widely varied mite materials and allergic sera, and biochemical and immunological assays, have isolated and characterized, to varying degrees, some of the allergens produced by these mites. The resulting large body of literature is difficult to interpret and relate. This review briefly summarizes the progress made in isolating and characterizing mite-derived antigens and allergens, the relationship between antigens isolated in different laboratories, and the patients' reactivity to these allergens. A brief summary of the allergic reaction and the role of IgE are provided as background.