Data from a subgroup of adolescents (12-17 years) entered into a one-year open-label phase of a large international study were analysed to evaluate response rates and tolerability of zolmitriptan for the acute treatment of migraine. In the open-label phase of this study, the first two migraine attacks were treated with zolmitriptan 2.5 mg and subsequent attacks with zolmitriptan 2.5 mg or 5 mg, at the patient's discretion, for up to 12 months. Two-hour headache and pain-free responses were evaluated and adverse events were recorded. Thirty-eight adolescents treated 276 migraine attacks of any intensity. The overall headache response at 2 hours was 80% (88% and 70% with zolmitriptan 2.5 mg and 5 mg, respectively), and the pain-free response was 66% (76% and 52% for zolmitriptan 2.5 mg and 5 mg, respectively). Response rates were independent of whether or not migraine was associated with aura or menses. During prolonged use, patients learned to adjust the dose of zolmitriptan to effectively manage their migraine. Treatment was well tolerated. In conclusion, preliminary data indicate that zolmitriptan is effective in the acute treatment of migraine in adolescents and is well tolerated.