SummaryTheDermatophagoidesmites are well recognized as allergens in bronchial asthma. A survey of mattress dust in Birmingham showed large numbers ofEuroglyphus mayneito be present in addition. A variation was found in mite populations in dust collected by vacuum cleaner when compared to brushed samples, which may explain previous findings of only small numbers ofE. maynei. A mean density of 296 pyroglyphid mites; 100 μg dust was found in mattress dust.Glycyphagusspecies formed only 1%, of all mites seen