 Individuals with obsessive compulsive disorder OCD often find inadequate relief, even with the best of currently available treatments. Some evidence suggests the the neurotransmitter glutamate may be a useful target for new treatments for OCD. The amino acid glycine, if given orally in adequate dosages, can have specific effects on one particular glutamate receptor molecule in the brain, that might be helpful with OC symptoms. This randomized, double-blind protocol will have study participants who suffer with OCD take either a glycine preparation or placebo for 12 weeks. Clinical measures e.g., Y-BOCS, NIMH-OC will be recorded at each visit to determine whether those taking the glycine experience clinical benefit. 