This study tested the effect of questionnaire structure on response, speed of return, and content of answers in a postal survey. All 259 patients aged 30-59 years who consulted with back pain at four UK general practices from March to June 2001 were randomly allocated to receive either a traditionally or chronologically structured self-completion questionnaire. The response was higher and the returns quicker (P =.05) for the chronologic questionnaire. There were no statistically significant differences in completion rates or scores on the SF-36, Chronic Pain Grade, Hospital Anxiety and Depression Scale, or Roland-Morris Disability Questionnaire between the two types of questionnaire, and test-retest reliability was high for all scales. Changing questionnaire structure to make questions chronologic does not substantially affect the answers given, but may make a questionnaire more acceptable and easier to complete and speed up returns.