In the International Headache Society (IHS) classification of 1988, chronic daily headache (CDH) forms are not exhaustively categorized. The forthcoming revision of the classification will include a number of CDH forms that had been reported prior to 1988 or have been identified after that date. In particular, chronic migraine will be added to the classification as a complication of migraine, provided that use of symptomatic drugs does not exceed 10 days per month. In addition to chronic cluster headache and chronic paroxysmal hemicrania, short-lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT) and hemicrania continua will be comprised among CDH forms with short-lived attacks. Hypnic headache will be included in Group 4 ("Other primary headaches"). No additions will be made to the new IHS classification for forms such as new daily persistent headache (NDPH) and cervicogenic headache as proposed by Sjaastad.