A survey in Israel of poultry houses at 35 different farms in four zones differing in climate was made to determine the prevalence, number and species of mites. Over an 18-months period, 240 samples were taken: 124 dust samples from dust-laden poultry house surfaces, and 116 soil samples from earth and litter adjacent to or containing poultry droppings. Mites were present in all of the poultry houses surveyed; in 92 % of dust samples and in 90 % of soil samples. More than 30 species were identified; as many as 796 mites per 100 mg of dust and 840 mites per 100 mg of soil were count_ed. In dust samples, the most prevalent species were Dermatophagoides evansi (74.4 %) and Acarus immobilis (5.6 %); and in soil samples: A. immobilis (40.9 %), D. evansi (11.4 %) and Hughesiella africana (9.2 %). The mite population in dust and soil samples was significantly (p < 0.05) higher in September. Significantly higher (p < 0.01) mite counts were noted in dust samples from the hottest and most arid region of the country. Great variation was noted in the number of mites in samples from the same climatic zone. Seventy-two percent of the pou ry farms reported the occurrence of workplace-related respiratory disease.