Obsessive-Compulsive Disorder (OCD) is a common neuropsychiatric condition. Many herbs with psychotropic effects exist which can have fewer side effects compared to more conventional medications. Valeriana Officinalis L. is a well-known medicinal plant with a long history of usage in the world with an effect on GABA. This plant is reported to be safe on humans. Our objective in this study was to compare the efficacy of the extract of Valeriana Officinalis L. with placebo in the treatment of OCD. The study was an 8-week pilot double-blind randomized trial. Thirty-one adult outpatients who met the DSM-IV-TR criteria for OCD based on the structured clinical interview participated in the trial. In this double-blind and randomized trial, patients were randomly assigned to receive either capsule of the extract (765 mg/day) or placebo (30 mg/day) for 8 weeks. The results showed significant difference between the extract and placebo in the end of treatment (P=0.000). Somnolence was the only significant difference between the two groups in terms of observed side effects (P=0.02). The results suggest that Valeriana Officinalis L. has some antiobsessive and compulsive effects. However, further studies are needed to confirm these findings. Psychiatrists often find that many patients cannot tolerate the side effects of psychiatry medicine Valeriana Officinalis L. is a well-known medicinal plant with a long history of usage in world with effect on GABA.The results showed significant difference between the extract and placebo in the treatment of OCD. There was also no significant difference between the two groups in terms of observed side effects.