ObjectiveThe aim was to describe the short-term (6 months) effects of olanzapine on behavioral and motor clinical manifestations in a group of 11 patients with Huntington disease.MethodAn open-pilot study of olanzapine (5 mg) in patients with clinical and genetic diagnosis of Huntington disease was used. The Unified Huntington Disease Rating Scale for clinical assessment and the Total Functional Capacity score for the disease-stage evaluation were used. A statistical analysis was performed to compare the effects of olanzapine on the Unified Huntington Disease Rating Scale scores at time 0 (baseline) and at time 1 (6 months). Comparisons of motor scores, of single behavioral items, and of TFC scores were performed within the group.ResultsThe behavioral assessment score of items regarding depression, anxiety, irritability, and obsessions showed a significant improvement (range ofp, 0.013–0.048). Given the total behavioral scores (sum of all the items investigated), five patients significantly improved their behavioral score after a 6-month treatment (range of p, 0.013–0.047). Choreic movements improved, although not significantly (0.05 ≤p≤ 1).ConclusionsOlanzapine is a potentially useful antipsychotic drug, with significant short-term effects on behavioral changes, mainly in patients with severe psychiatric symptoms at the onset. It might be considered as a possible therapeutic choice for treatment of Huntington disease.