Rizatriptan is a selective 5-hydroxytriptamine1B/1D receptor agonist that was launched in 1998 for the acute treatment of migraine in adults. Based on data from 6 large clinical trials in patients > or =18 years of age in whom migraine was diagnosed according to International Headache Society criteria, the marketed 10-mg and 5-mg oral doses of rizatriptan are effective in relieving headache pain and associated migraine symptoms. The 10-mg dose is more effective than the 5-mg dose. At 2 hours after dosing, up to 77% of patients taking rizatriptan 10 mg had pain relief compared with 37% of those taking placebo, up to 44% were completely pain free compared with 7% of those taking placebo, and up to 77% were free of nausea compared with 58% of those taking placebo (P < 0.05 for all 3 comparisons). Both doses of rizatriptan are generally well tolerated. In placebo-controlled studies involving treatment of a single migraine attack, the most common side effects (incidence > or =2%) occurred in <10% of patients, typically were transitory (2 to 3 hours), and were mild or moderate. Rizatriptan is an effective and well-tolerated acute treatment for migraine.