The aim of this study was to investigate the prevalence and determinants of self-reported neck or shoulder pain (NSP) and low back pain (LBP) among 12-18-year-olds. A questionnaire was mailed to a nationally representative sample of 11,276 12-, 14-, 16- and 18-year-olds in 1991. The response rate was 77%. NSP was perceived at least once a week by 15% of 12-18-year-olds and LBP by 8%. Both symptoms were more prevalent among girls than among boys, and the prevalence increased with age. Among the determinants investigated, the number of perceived psychosomatic symptoms had the strongest association with NSP and LBP. Our study confirmed the co-morbidity of NSP and LBP, and indicated that NSP is more frequent than believed among 16-18-year-old girls. The strong association of psychosomatic symptoms with NSP and LBP suggests that the latter two pain states could be more psychosomatic than nociceptive in character.