BACKGROUND Eletriptan is a potent 5-HT(1B/1D) agonist with proven efficacy in the acute treatment of migraine in adults. OBJECTIVE To evaluate the efficacy and tolerability of eletriptan 40 mg versus placebo in adolescent patients (aged 12-17). METHODS A multicenter, double-blind, parallel-group, placebo-controlled trial was conducted comparing 40 mg of oral eletriptan with placebo for the treatment of migraine in adolescent patients. The primary efficacy endpoint was 2-hour headache response, and a number of secondary endpoints were also evaluated. An exploratory analysis evaluated which clinical and demographic characteristics might be correlated with high placebo response. RESULTS Of 274 patients who treated a migraine attack, 267 were evaluated for efficacy (n = 138 eletriptan; n = 129 placebo) at 2 hours post-dose. There was no significant difference in 2-hour headache response for eletriptan 40 mg versus placebo (57% vs 57%), and no significant improvements were observed for any of the outcomes at 1 or 2 hours post-dose. By contrast, there was a significant advantage for eletriptan 40 mg in reducing headache recurrence within 24 hours post-dose (11% vs 25%, P= .028), and post hoc analyses showed statistically significant differences for sustained headache response rates (52% vs 39%; P= .04) and sustained pain-free response rates (22% vs 10%; P= .013). The strongest clinical predictor of placebo response was triptan-naïve status (i.e., no previous use of any triptan). Eletriptan 40 mg was well tolerated in this population, and the profile of adverse events was similar to that observed in Phase III trials in adult patients. CONCLUSIONS The high placebo response rates reported here for 1- and 2-hour outcomes are in accordance with other studies of triptans in adolescent patients. The evaluation of treatment effect in adolescent migraine might benefit from use of more stringent outcome measures, such as headache recurrence, sustained headache response, and sustained pain-free response at 24 hours post-dose.