In this overview of investigations into mite allergy in Iceland and of the current understanding of the sources of exposure, 2 major categories of mite-induced allergies were encountered. The first was house dust mite allergy due to house dust mites from unknown sources, and the second was barn allergy caused by mites connected with the degradation of stored hay. Characteristics of these diseases have been obtained from surveys where skin prick tests were made with commercially available extracts of mites and from zoological investigations where mites had been found in different kinds of dusts relevant for the tested persons. The investigations uncovered a discrepancy between the capital Reykjavik and countryside farms. While the frequencies of sensitization to house dust mites and barn mites are rather similar in the capital area and in the rural area, the exposure to these mites is unexpectedly low in the capital area. Thus, sensitization appears to take place preferably in the rural area.