Inclusion Criteria:  experiencing clinically significant obsessive-compulsive symptoms based on the Yale-Brown Obsessive Compulsive Scale (YBOCS; score > 17) if on medications for OCD, must be stabilized, i.e. are currently receiving an adequate dose (equivalent of 40mg/day of fluoxetine) for an adequate duration (at least 8 weeks of treatment) prior to the initiation of the study.  Exclusion Criteria:  concurrent diagnosis of a severe mood disorder, schizophrenia or other psychotic disorders, or substance abuse/dependence suspected organic pathology an active comorbid medical condition that may require urgent intervention during the treatment.