One-hundred-and-eighty-nine cluster headache patients, referred to Parma and Pavia Headache Centres between 1976 and 1986 with a disease duration of over 10 years, were interviewed about the course of cluster headache. They were classified as episodic (n = 140) or chronic (n = 49) cluster headache patients on the basis of course during the year of onset. Episodic patients showed the following outcome: maintenance of an episodic form (primary episodic form) in 80.7% of cases, shift towards a chronic form (secondary chronic form) in 12.9% and shift towards an intermediate pattern ("combined" form) in 6.4%. In chronic patients, cluster headache was still chronic (primary chronic form) at the moment of observation in 52.4% of cases, while it turned into an episodic form ("secondary" episodic form) in 32.6% and into a "combined" form in 14.3%. Nineteen patients (10%) had had no attacks for at least three years at the moment of examination. We can conclude from our data that: cluster headache is a disease of long duration, perhaps lifelong; episodic cluster headache tends to worsen; chronic cluster headache may easily turn into a better prognostic episodic form; prophylactic drugs are unable to induce recovery. The following factors seem related to a poor outcome: a later onset, the male gender and a disease duration of over 20 years for the episodic forms.