Premenstrual syndrome (PMS) affects most women during their reproductive life. Headache is regarded as a typical symptom of PMS and, close to menses, migrainous women could experience their worst migraine attacks. Vitex agnus-castus (VAC) is a phytopharmaceutical compound, considered worldwide to be a valid tool to treat PMS. Aim of this study is to explore if headache is ameliorate in migrainous women treated with VAC for PMS by an open-label clinical observation. Migrainous women with PMS were enrolled in the study and advised to assume a treatment with VAC (40 mg/day) for PMS for a 3-month period. Effects both on PMS and headache were assessed. Out of 107 women, 100 completed the 3-month treatment for PMS. Out of them, 66 women reported a dramatic reduction of PMS symptoms, 26 a mild reduction, and 8 no effect. Concerning migraine, 42 % of patients experienced a reduction higher than 50 % in frequency of monthly attacks, and 57 % of patients experienced a reduction higher than 50 % in monthly days with headache. No patients reported remarkable side effects. Pending a placebo-controlled trial to confirm our results, we observed that the use of VAC in migrainous women affected by PMS resulted to be safe and well tolerated, and may positively influence the frequency and duration of migraine attacks.