The efficacy of 5-hydroxytryptophan and propranolol has been studied in the interval treatment of migraine. 39 migraine patients have participated in a double-blind trial. After a placebo run-in of one month, the patients received either 5-hydroxytryptophan or propranolol for 4 months. The treatment with both substances resulted in a statistically significant reduction in frequency of migraine attacks. Furthermore, in the propranolol group the duration of the attacks and the number of analgesics used for treatment of the attacks were significantly reduced. Although propranolol, which is considered a reference for the interval treatment of migraine, is more effective, 5-hydroxytryptophan is a possible alternative for many patients.