INTRODUCTION: In France, most studies of low back pain (LBP) have been carried out among workers or patients. Until very recently, the frequency of LBP in the general population was not known, because National Health Surveys did not include questions on LBP. OBJECTIVE: To estimate the prevalence of LBP in the French population aged 30 to 64 years. MATERIALS AND METHODS: The main data were from the National Health Survey 2002-2003 (n=14,248). LBP was assessed by an accompanying self-administered questionnaire asking details about duration of LBP in the previous 12 months. Weights were used to estimate the prevalence of LBP in the French population, with two definitions of LBP. Additional results dealing with chronic LBP, from another national survey (Handicap, Disability and Dependence), are also briefly presented. RESULTS: More than half of the French population in this age group experienced LBP at least one day in the previous 12 months (LBP1), with 17% experiencing LBP for more than 30 days in the previous 12 months (LBP30); prevalence differed between men and women and that of LBP30 increased with age. DISCUSSION-CONCLUSION: The prevalence of LBP as assessed by the National Health Survey is similar to that found in countries other than France. These estimates can be used as a reference for surveys in specific populations, provided that comparable methodologies are used.