Temporormandibular disorders (TMD) and tension-type headaches (TTHA) share many signs and symptom and several studies have demonstrated an overlap between these conditions. Objectives: This study investigated the relationship of headache frequency with patient-reported TMD pain intensity, physical functioning, and emotional functioning in subjects with TTHA attributed to TMD. Methods: The RDC/TMD Validation Project, as a subset of 633 TMD cases, identified 153 subjects with concurrent TMD pain diagnoses (RDC/TMD myofascial pain or TMJ arthralgia) and TTHA (International Classification of Headache Disorders-II / ICHD-II) presenting in the temporal region. These subjects also demonstrated pain similar to their headache on provocation by palpation of the temporalis muscle. The headache diagnoses were sub-divided into infrequent episodic, frequent episodic, and chronic TTHA according to the ICHD-II. Outcomes of the study were self-report measures of jaw pain intensity (average pain intensity), physical functioning (Jaw Function Limitation Scale/JFLS, Ohrbach et al, 2008; Graded Chronic Pain Scale/GCPS, von Korff et al, 1992; Short Form -12/SF-12, Ware et al, 1996) and emotional functioning (depression, somatization, anxiety as measured by the Symptom Checklist-90/SCL-90). Differences in outcomes among the three headache subgroups were investigated using ANOVA. Results: Pain intensity in the temple and jaw regions was significantly associated with increased frequency of headache (p<0.01). Physical functioning as assessed with the JFLS (p<0.05) and the GCPS (p<0.01) were also significantly associated with headache frequency. Emotional functioning as assessed with the SCL-90 in terms of depression, somatization, and anxiety were all associated with frequency of headache (p<0.05). In general, the more frequent a subject's TTHA the more severe the levels of outcome. Conclusion: TMD pain intensity, physical functioning, and emotional functioning were associated with the frequency of TMD-related tension-type headache.