The objective of this study was to obtain preliminary open-label data on the efficacy and tolerability of memantine, an anti-glutamatergic medication with a unique pharmacodynamic profile, in individuals with OCD and individuals with GAD. Because glutamatergic hyperactivity in frontal and frontal-subcortical circuits may play a role in the symptomatic expression of OCD, and possibly GAD, agents that reduce glutamatergic neurotransmission should provide unique anti-stress and anti-obsessional benefits. Memantine is a specific, uncompetitive antagonist at the NMDA receptor that blocks sustained activation of the NMDA receptor by high concentrations of glutamate under pathological conditions but rapidly leaves the NMDA channel upon transient physiological activation by low concentrations of glutamate.