The purpose of this paper is to present the results of a questionnaire investigating parafunctions (particularly clenching and grinding) in patients with chronic migraine presenting sign of temporomandibular disorder. The questionnaire was elaborated by the Dental Clinic of the University of Milano and completed by 125 patients experiencing chronic migraine and attending the Neurological Institute Carlo Besta for an inpatient withdrawal protocol to treat medication overuse. Our results showed high percentages of parafunctions, which were present in 80 % of patients. We note that patient information on possible behaviours and coexisting conditions which may be involved in the mechanisms of chronic headaches, as well as education about these factors, are crucial aspects in the management of chronic headache patients. We suggest that patients suffering from chronic migraine with medication overuse headache should be evaluated in relation to the possible presence of parafunctions, and as far as the need for interocclusal devices, in order to limit the role of temporomandibular dysfunctions as trigger factors or coexisting conditions favouring the development/maintaining of headache chronification.