A single oral dose of 500 mg sodium valproate had no effect on prolactin, growth hormone and cortisol secretion in 10 migraine patients when compared with five healthy controls and four migraine patients receiving placebo. Basal values of prolactin (PRL), cortisol and growth hormone (GH) were within the normal range, though PRL basal levels were lower in three patients (21.5%) in the migraine group.