OBJECTIVE: The present study is aimed at determining the percentage of temporomandibular joint disorder (TMD) in patients admitted to the neurology outpatient clinic with a headache complaint and to evaluate the association of TMD with the presence of bruxism and headache traits. MATERIALS AND METHODS: A total of 349 headache patients were included in the study. The headache type, characteristics of the headache (incidence, duration, and severity of attacks), and the scores of the migraine disability scale (MIDAS) and Allodynia Symptom Scale (ASC-12T) were examined considering the presence of sleep bruxism. The International Classification of Headache Disorders (ICHD-3 Beta) criteria were used for diagnosing headaches. The presence of TMD was evaluated by using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). All patients diagnosed with TMD and/or bruxism were evaluated by a dentist. RESULTS: A total of 349 patients, 259 females and 90 males, were included in the study. The mean age of the patients was 36 years. Primary and secondary headaches were diagnosed in 317 (90.80%) and 32 (9.20%) patients, respectively. In the primary headache group, there were 227 migraines (182 females, 45 males), 74 tension-type headaches (TTH) (48 females, 26 males), and 15 trigeminal autonomic cephalalgias (TACs) (7 females, 8 males) patients. The remaining patients were diagnosed with other types of diagnoses. The rate of patients with chronic headache was 86.50%. TMD was detected in 89 (25.50%) of the patients while sleep bruxism was present in 80 (23.30%) patients. TMD was detected in 68 (30.0%) migraine patients and 13 (17.60%) TTH patients. The rate of TMD was statistically significantly higher in migraine patients compared to the TTH patients (p=0.037). CONCLUSION: Our cross-sectional outpatient-based study determined the incidence of TMD in headache patients as 25%. Among the primary headaches, the incidence of TMD was higher in migraine patients compared to the other diagnoses. Considering these data, the presence of TMD is a clinical condition that should be considered in the pathophysiology of headache, primarily migraine, and especially in cases of non-response to treatment.