The pathophysiology of tension-type headache is still far from clear, although recent advances in basic and clinical research have increased our knowledge about mechanisms underlying this disorder. Experimental studies suggest that increased excitability of the CNS generated by repetitive and sustained pericranial myofascial input may be responsible for transformation of episodic tension-type headache into chronic form. Future studies should focus on the identification of the source of peripheral nociception in patients with tension-type headache and the development of more effective and specific treatment modalities.