The treatment of chronic cluster headache is based on a few proven drugs, namely lithium salts, corticosteroids, methysergide maleate, and verapamil hydrochloride.1 However, some patients do not stop having attacks, despite treatment with 1 or more of these drugs. More recently, transdermal clonidine was proposed as a possible effective and safe treatment.2 This drug may act by reducing the sharp fluctuations of the sympathetic nervous system occurring during the attacks,3 by inhibiting the central sympathetic pathway. Tizanidine, an imidazoline derivative, usually used as a central muscle relaxant, is structurally similar to clonidine and seems to act through central α2-receptor agonistic activity.4 We treated 5 consecutive patients with chronic cluster headache resistant to previous treatments with tizanidine as add-on therapy. Results are summarized in the Table. In 3 patients the attacks ceased and any other treatment was discontinued, in 1 there was a marked reduction