The present invention relates to the use of fruit extract from Vitex agnus castus and/or one or more isolated and/or synthetically prepared bicylic diterpenes from Vitex agnus castus for the preparation of a medicament for the treatment of movement disorders. In particular, the invention is directed to the preparation of medicaments for treating Parkinson disease (PD), Periodic Limb Movement disorder (PLMD) and Restless Leg Syndrome (RLS), Huntington disease (HD) and Essential Tremor (ET), preferably familiar ET. Furthermore, the invention concerns a pharmaceutical composition comprising a fruit extract from Vitex agnus castus and/or one or more isolated and/or synthetically prepared bicylic diterpenes from Vitex agnus castus and at least one pharmaceutically compatible dopamine D2 and/or D3 receptor agonist.