We have evaluated the association between headache and musculoskeletal symptoms in a large cross-sectional population-based study. Between 1995 and 1997, all 92 566 adults in Nord-Trøndelag County in Norway were invited to participate in a health survey. A total of 51 050 (55%) responded to questions concerning headache and musculoskeletal symptoms. Both migraine and non-migrainous headache were strongly associated with musculoskeletal symptoms. However, frequency of headache had a higher impact than headache diagnosis on this association. Thus, the prevalence of chronic headache (headache >14 days/month) was more than four times higher (OR = 4.6; 95% CI 4.0-5.3) in the group of individuals with musculoskeletal symptoms than in those without. Individuals with neck pain were more likely to suffer from headache as compared with those with musculoskeletal symptoms in other restricted areas. In conclusion, there was a strong association between chronic headache and musculoskeletal symptoms, which may have implications for the choice of treatment.