The rates of moving out (out-migration) and of response to self-administrated questionnaire on respiratory symptoms were surveyed about 3600 inhabitants, who had participated in the first one during their school childhood, living in the town located in rural district of Hokuriku area. Out of the cohort of junior high schoolchildren at the 1st grade at the first survey 53.4% of male and 26.5% of female lived in the same town at 20th years survey when their age was 30-31 years old. The former was significantly higher than the latter (p<0.01). The rate was significantly higher of the male inhabitants in the agricultural district (64.4%) of the town compared with in the downtown district (47.4%), (p<0.01). The response rate to the 20th year survey, related neither to gender nor age, but related to the district. It was 87.6% in the agricultural district and 76.6% in the downtown. Significant difference was observed (p<0.05) between the percentages. Due to moving out and non-response to the questionnaire, participation in the 20th year survey were 40s% out of primary schoolchildren in the 1st grade, and 50s% of male out of the junior high schoolchildren and 20s% of female out of the primary schoolchildren in 1st grade. Considerable number of schoolchildren moves out of the original living districts until the age of their adolescent because of entering into higher schools, getting jobs, getting into marriage and so on. It is important for the cohort survey to prepare some devices to maintain a higher response rate involving the out migrants.
