This work assesses the differences in the thermographic findings in the craniofacial and neck areas between normal individuals and patients with craniofacial pain or headache, and investigates the influence of muscle contraction on such findings. Thermographic records were taken in 10 healthy subjects and 47 patients suffering from craniofacial pain or headache of different kinds. In the patients with painful episodes the record was taken between attacks. In all the normal subjects and in 19 patients lateral thermograms were also taken during and after maximal tooth clenching for three minutes. The majority of the patients, as compared to the normal group, showed some thermal alterations and asymmetry. Such alterations seem to be due both to vascular instability and muscle contraction: these two factors may be variably superimposed in the different conditions. In patients with cluster headache or chronic paroxysmal hemicrania the presence on the symptomatic side of a cold spot along the supraorbital area and/or the inner orbital canthus, was a constant finding. We conclude that thermography is useful as an additional diagnostic means in patients with head and face pain, and that the clenching test may increase the amount of information provided.