Premenstrual syndrome (PMS) is a condition of cyclical and recurrent physical and psychological discomfort occurring 1 to 2 weeks before menstrual period. More severe psychological symptoms have been described for the premenstrual dysphoric disorder (PMDD). No single treatment is universally recognised as effective and many patients often turn to therapeutic approaches outside of conventional medicine. This systematic review is aimed at analysing the effects of herb remedies in the above conditions. Systematic literature searches were performed in electronic databases, covering the period January 1980 to September 2010. Randomised controlled clinical trials (RCTs) were included. Papers quality was evaluated with the Jadad' scale. A further evaluation of PMS/PMDD diagnostic criteria was also done. Of 102 articles identified, 17 RCTs were eligible and 10 of them were included. The heterogeneity of population included, study design and outcome presentation refrained from a meta-analysis. Vitex agnus castus was the more investigated remedy (four trials, about 500 women), and it was reported to consistently ameliorate PMS better than placebo. Single trials also support the use of either Gingko biloba or Crocus sativus. On the contrary, neither evening primrose oil nor St. John's Wort show an effect different than placebo. None of the herbs was associated with major health risks, although the reduced number of tested patients does not allow definitive conclusions on safety. Some herb remedies seem useful for the treatment of PMS. However, more RCTs are required to account for the heterogeneity of the syndrome.