Background: An open-label trial was performed to explore efficacy and safety of olanzapine, an atypical neuroleptic with diverse receptor activity including both dopamine-2 and serotonin-2A and -2C antagonism, for treatment of Tourette's disorder. Method: Ten adult patients aged 20 to 44 years with Tourette's disorder were treated using an open-label, flexible dosing schedule for 8 weeks. Three patients who continued olanzapine were reevaluated after 6 months. Three subjects were psychotropic medication naive, 5 patients experienced intolerable side effects with conventional neuroleptics, and 2 patients had remote (greater than or equal to 10 years) successful response to conventional neuroleptics. Tic severity was rated by the Yale Global Tic Severity Scale; weight, vital signs, and adverse effects were assessed weekly. Electrocardiogram, laboratory studies, and comorbid symptoms, assessed by the Yale-Brown Obsessive Compulsive Scale and ADHD Behavior Checklist for Adults, were measured at baseline and at week 8. Results: Two of 10 patients prematurely discontinued olanzapine owing to excessive sedation. Of 8 patients who completed the 8-week trial, 4 (50%) demonstrated reduction of global tic severity scores by greater than or equal to 20 points, and 6 (75%) demonstrated reductions by greater than or equal to 10 points. No significant changes in comorbid symptoms were demonstrated. Sedation, weight gain, increased appetite, dry mouth, and transient asymptomatic hypoglycemia were the most common side effects. Tic improvements were maintained in 3 patients reassessed 6 months later. Final olanzapine dosages ranged from 2.5 mg to 20 mg daily (mean = 10.9 mg/day). Conclusion: This open-label study suggests that olanzapine should be explored as a potential alternative to conventional neuroleptic medications for treatment of motor ties and Tourette's disorder.