 This pilot study is proposed to determine the acceptability, feasibility and potential efficacy of ketamine, a medication that modulates glutamate in the brain, as a rapid treatment for obsessive-compulsive disorder OCD symptoms in adolescents and young adults with OCD. This study will recruit 6 youth ages 14-22 who are diagnosed with clinically significant OCD and have failed at least one adequate trial of a Serotonin Reuptake Inhibitor SRI medication and a course of Cognitive-Behavioral Therapy CBT unless unable to access or tolerate for OCD in the past. Participants will receive a single infusion of intravenous ketamine and be assessed at regular intervals post-infusion for up to 14 days. At the end of the 14-day treatment phase, all participants will be offered three months of open treatment for OCD with medication andor CBT. 