Eosinophil inflammation is a common feature of allergic disorders and particularly in allergic asthma interest has been paid to related markers. In a community-based survey of 10-year-old children, the association of eosinophil count (EC) and serum eosinophil cationic protein (ECP) with allergic sensitization, clinical history and exposure to mite allergen was studied. Relying on the results of skin prick tests, the children were divided to three groups: (1) children showing no sensitization to one of the seven inhalant allergens (n = 16); (2) children with sensitization to at least one of five non-mite allergens (n = 16); and (3) children with sensitization to mite allergens (n = 75). Clinical history of asthma and hay fever was ascertained using standardized questionnaires. EC in peripheral blood and serum ECP were measured on one single occasion. Prior to blood sampling, mite allergen exposure at home had been assessed by taking dust samples and measuring the mite antigen concentration by means of an enzyme immunoassay. Compared to group 1, higher ECs were obvious in group 2 (P = 0.037) and in group 3 (P = 0.0013). Regarding serum ECP, higher levels occurred in group 2 (P = 0.0033) as well as in group 3 (P = 0.0001) when comparing them to the reference group. Sensitized children with neither asthma, nor asthma-like symptoms, nor hay fever (n = 28) did not have significantly lower ECs and serum ECP levels than those with hay fever (n = 15; P = 0.09, P = 0.17) and those with asthma (n = 22; P = 0.69, P = 0.64).(ABSTRACT TRUNCATED AT 250 WORDS)