Baclofen, an analog of the putative inhibitory neurotransmitter gamma-aminobutyric acid is capable of crossing the blood-brain barrier. The drug has been shown to have an antinociceptive action and is used effectively in the management of spasticity. Baclofen was first used in the treatment of trigeminal neuralgia in 1980 and is currently used in the management of various types of neuropathic pain. The effect of baclofen on migraine has not been previously studied. The aim of the present open pilot study was to evaluate the efficacy of baclofen in patients with migraine. Fifty-four patients with migraine with and without aura who experienced 4-8 migraine attacks during a 4-week baseline were included. Baclofen, 15-40 mgs, was given in three divided doses for 12 weeks. Headache frequency and severity were recorded. Fifty-one patients completed the trial. Baclofen was found to be effective in 86.2% with > or = 50% headache reduction from baseline. Three patients could not tolerate the drug due to adverse events. In this open study, baclofen was found to be effective for prophylactic treatment of migraine.