We studied the association of chronic headache and chronic rhinosinusitis in 30,000 persons aged 30-44 years from the general population. They received a mailed questionnaire. Those with possible chronic headache were interviewed by neurological residents. The criteria of the American Academy of Otolaryngology--Head and Neck Surgery were applied to diagnose headache attributed to chronic rhinosinusitis (HACRS), otherwise the International Classification of Headache Disorders was used. The questionnaire response rate was 71%, and the participation rate of the interview was 74%. Compared with the general population, persons with chronic rhinosinusitis have an at least ninefold increased risk of having chronic headache. A 3-year follow-up showed that HACRS symptoms were significantly improved after treatment with nasal surgery, nasal corticosteroids, discontinuation of overused headache medications and discontinuation of nasal decongestants or unspecified reasons. Chronic rhinosinusitis is significantly associated with chronic headache, and HACRS is likely to be a distinct type of headache.