The clinical effects of the protracted treatment with 5-OH Tryptophane (5-HTP) of some patients with chronic migraine are compared with other patients with acetylsalicylic acid. The pain threshold was neurophysiologically determined in migraneous on patients whose response to 5-HTP therapy was specially good. The results with 5-HTP can be accounted for by an action of the substance on the serotonin turnover with activation of the serotoninergic antinociceptive system.