The occurrence of atopic diseases in school children in the community of Sør-Varanger was studied on the basis of a questionnaire sent to the parents of all the 575 children aged 7-12 years. 551 children (95.8%), 266 girls and 285 boys, completed the questionnaire. Atopic diseases were reported to be present or to have occurred in 249 (45.2%) of the 551 children, more frequently in girls (50.4%) than in boys (40.4%) (p < 0.02). Asthma occurred in 68 cases (12.3%), with almost the same frequency in girls (13.2%) and boys (11.2%). Allergic rhinoconjunctivitis was detected in 113 children (20.6%); it was slightly more frequent in boys (21.8%) than in girls (18.9%) but did not reach statistical significance. Urticaria occurred in 72 cases (13.1%), more frequently in girls (17.7%) than in boys (8.8%) (p < 0.002), while atopic dermatitis occurred in 130 cases (23.6%), again more frequently in girls (27.6%) than in boys (19.6%) (p < 0.03). Ninety-four (37.8%) of the children experienced more than one atopic symptom. In 75% of the children with dermatitis the age at onset was under 5 and more than 50% of the children with asthma had experienced symptoms before the age of 3. Parental history of atopic diseases was reported by 35.6% of all children, more frequently in mothers (30.2%) than in fathers (20.1%). On the other hand, 30.6% of children with no parental history of atopic diseases appeared to develop some kind of atopic disease; this increased to 48.0% with a single and to 56.1% with a double parental history.(ABSTRACT TRUNCATED AT 250 WORDS)