 The goal of the proposed study is to evaluate the efficacy and safety of the drug memantine in individuals with pathological gambling PG. Thirty subjects with DSM-IV PG will receive 10 weeks of open-label treatment with memantine. The hypothesis to be tested is that memantine will be effective and well tolerated in patients with PG. We hypothesize that memantine will reduce the severity of gambling symptoms and improve patients overall functioning. This study will provide needed data on the treatment of a disabling disorder that currently lacks a clearly effective treatment. 