The clinical and therapeutic aspects in 26 patients with cluster headache are reported. The patient's age ranged between 14 and 60 years old (average 31.5 years); 22 were male and 4 female. The patients constitued a consecutive series of typical cases (only one was a chronic cluster) with regular headache attacks; in 69.2 per cent of the cases there were associated symptoms and signs (ipsilateral lacrimation, stuffiness of the ipsilateral nostril and Horner's syndrome). In seven patients the cluster was induced by alcohol ingestion (during an active cluster period) and a cluster attack was reproduced by isosorbitol dinitrate (vasodilatador drug) in one patient. All patients received orally either methysergide maleate, prednisone or both. The first drug used, in 20 patients, was methysergide maleate in a dosage of 3-6 mg daily over a four weeks period. Eight patients received prednisone only, which presented side-effects or no improvement with methysergide, in a dosage of 40-60 mg daily and tapered off over a period of four weeks. Methysergide maleate and prednisone were given to 11 patients in association, because of moderate effect of the first drug. The clinical effect of the treatment was judged according to the following three categories: freedom from the attacks; slight improvement of the attacks; no improvement of the attacks. In 57.6 per cent of the cases (15 patients) there was freedom of the attacks, in 30.7 per cent of the cases (8 patients) there was a slight improvement and in 3 patients there was no improvement.