The aim of this prospective open label study was to assess the efficacy of olanzapine for motor symptoms in Huntington's disease (HD). Olanzapine was administrated to nine patients with genetically confirmed HD in increasing doses until satisfactory clinical effect or the appearance of side effects. The patients were evaluated at baseline and after 14 days of treatment using the motor scale of the Unified HD Rating Scale (UHDRS). The patients improved significantly in most subscores of the UHDRS, including fine motor tasks, although some patients needed a rather high dose (30 mg per day). No adverse effects were reported by the patents spontaneously or were observed directly by the investigator. High-dose olanzapine seems to be useful in choreatic HD patients. A double blind, placebo-controlled trial appears warranted to definitively establish the symptomatic value of olanzapine in HD.