The aim of this cross-sectional study was to explore associations between self-reported leisure activities and low back pain (LBP). The material included all adolescents in eighth and ninth grade in two geographical areas in the school year 1996-1997. Eighty-eight adolescents participated (mean age 14.7 years), making the response rate 84%. LBP during the preceding year was reported by 57%. Sixty-six percent reported physical activity 3 times weekly or more. The median time spent on television or computer was 15 h. In multivariate analyses, LBP was inversely associated with time spent on physical activity, in particular with regular walking or bicycling. LBP was associated with the use of television or computer more than 15 h weekly, but not with the time spent reading. The results confirm studies showing inverse associations between walking and LBP. Future research should involve prospective studies of the potential effects of walking or bicycling and other specific activities on LBP.