The marked male predominance of Tourette’s syndrome suggests that androgens may play a key role in the pathophysiology of this disorder. Accordingly, androgen receptor antagonists, such as flutamide, significantly attenuate Tourette’s syndrome symptoms (2), yet their efficacy is hindered by severe side effects. A valid alternative to reduce androgen brain signaling may be afforded by inhibitors of 5-alpha-reductase (5-AR), the main rate-limiting enzyme in androgen metabolism. Thus, we tested the efficacy of finasteride, the prototypical 5-AR inhibitor, in a Tourette’s syndrome patient who was unresponsive to traditional therapy. Finasteride is approved for the treatment of benign prostatic hyperplasia and alopecia; it is psychoactive and produces very limited side effects.