The possible role of human dander in house dust allergy was investigated. Naturally shed human mite-free skin squames were collected from bedding and used to prepare a human dander extract. When the extract was coupled to cyanogen bromide-activated paper discs, and used in the RAST assay, IgE titres to the skin extract were observed in the sera from several patients with house dust allergy. The sera with IgE to the skin extract also had high IgE titres to either house dust, D. pteronyssinus or cat fur. RAST inhibition studies revealed cross-reaction between the human skin extract and both a D. pteronyssinus extract and a cat fur extract.