House dust sensitivity is a common precipitating cause of naso-respiratory allergy in Barbados. A high degree of correlation between skin tests to house dust and to mite extracts was found. The pyroglyphid species Dermatophagoides pteronyssinus occurred in high densities in samples of mattress and bedroom dust. Twenty-two other species of mites were identified in the dust samples and in certain cases some of these species were more abundant than D. pter. Skin tests were positive in a high proportion of dust sensitive asthmatics tested with extracts prepared from five species of mite in addition to D. pter. and D. farinae. There appears to be a relationship between the density of D. pter. in mattress dust and allergy to house dust.