Two standardized respiratory questionnaires in a Japanese version were given to 460 subjects randomly selected from male, middle-aged inhabitants of 15 villages in the Kashima district of Ibaraki Prefecture, Japan. One half of the men were given the questionnaire developed by the British Medical Research Council first and the questionnaire developed by the American Thoracic Society after an interval of about 2 weeks. The other half were given the questionnaires in reverse sequence.
For questions with similar wording, the two questionnaires yielded very similar results, and in terms of the over-all prevalence of symptoms, no important differ-ences were found between the two questionnaires. However, there were not a few subjects whose individual responses to similar questions in the two questionnaires were not the same. The results seemed to be partly explained by unstable res-ponses of subjects who complained of a symptom to only a slight extent.