EMG analysis of the late exteroceptive suppression period of the temporal muscle activity is discussed as comparative methodology in the assessment of patients suffering from chronic tension-type headache and from migraineurs. After electrical perioral trigeminal nerve stimulation during maximum voluntary jaw occlusion, early (ES1) and late (ES2) exteroceptive suppression periods can be registered above the temples using surface EMG recordings. In patients suffering from chronic tension-type headache the duration of the late suppression period is shortened (p less than 0.001) compared to migraineurs or controls. However, patients suffering from episodic tension-type headache display late suppression periods of temporal muscle activity of differing lengths.