Topiramate treatment was associated with rapid improvement in 10 cluster headache patients. Cluster remission occurred in 1–3 weeks in 9 patients, and cluster period duration was reduced in all. The mechanism for this response may be related to gamma-aminobutyric acid (GABA) augmentation. However, further investigations are necessary to understand the significance of topiramate in treating cluster headache. The use of anticonvulsant medications in chronic pain management is not new. Anticonvulsants have several uses outside of the epilepsies, and there has been resurgence in their use for chronic pain. This particularly applies to such recently approved anticonvulsants as gabapentin, lamotrigine, and topiramate. Factors that contribute to this trend in anticonvulsant use include ease of use, favorable pharmacokinetic and side effect profiles, multiple potential mechanisms of action, and the intractable nature of chronic pain. Cluster headache is an uncommon, benign, primary headache disorder characterized by severe, short duration, unilateral, orbital-temporal pain; ipsilateral autonomic dysfunction; and chronobiological disturbances.1 Although treatment is usually successful, some patients have intractable pain. Valproate has shown efficacy in cluster headache, and a role for GABA augmentation has been suggested.2-4 Because topiramate appears to augment GABA,5-7 we hypothesized that it may be efficacious in cluster headache. We report the clinical findings in 10 cluster headache patients whose conditions improved when they took topiramate. Two patients had chronic cluster headache unremitting from onset (Patients 1 and 2), seven …