• The primary efficacy measure will be be the YBOCS-PG total score. [ Time Frame: Efficacy will be determined by measuring the change in the total YBOCS-PG score from Baseline (visit 2) to the end of treatment at week 12 (visit 8). ] [ Designated as safety issue: No ]
  

• The secondary efficacy evaluations will include the GSAS, CGI-R, GAS, and the CGI-S. [ Time Frame: Efficacy will be determined by measuring the change from Baseline at Visit 2 to the end of treatment at Visit 8 (week 12). ] [ Designated as safety issue: No ]
  

Because the opiate antagonists appear to be effective in the treatment of pathological gambling (PG), it is reasonable to ask whether acamprosate (calcium acetylhomotaurine; Campral), also FDA approved for the treatment of alcoholism, can be used effectively to treat PG. Acamprosate is not an opioid antagonist; rather, it is assumed that its therapeutic effects are due to actions on GABA receptors. Acamprosate is structurally related to 1-glutamic, which is an excitatory neurotransmitter. It has been proposed that acamprosate decreases the effects of the naturally-occuring excitatory neurotransmitter glutamate in the body. Because chronic alcohol consumption disrupts this system, and the changes last many months after alcohol ingestion is stopped, it is possible that acamprosate restores the glutamate system towards normal. Regardless, acamprosate decreases the pleasant "high" associated with alcohol consumption, and thus decreases the frequency of relapse during abstinence. We hypothesize that acamprosate will have similar actions in persons with PG.

Inclusion Criteria:

• Patients will meet DSM-IV criteria for Pathological Gambling Disorder
• Patients will achieve a SOGS score greater than or equal to 5
• Patients will be 18 years old or older
• Patients will speak standard English
• Patients will be able to give written Informed Consent
• Patients will be able to understand and cooperate with study procedures

Exclusion Criteria:

• Patients having a current (past 3 months)substance use disorder (except dependence)
• Patients having a Hamilton Depression Rating score of greater than or equal to 18 or a score on #1 (depressed mood) greater than 1.
• Patients having a clinically significant medical illness
• Patients at risk for aggressive or suicidal behavior
• Patients who have received the following interventions within the proscribed time prior to study entry: 1) a monoamine oxidase inhibitor within the previous 21 days; 2) long-acting phenothiazines within the previous 3 months; 3) other psychotropic drugs within the previous 14 days; 4) flu- oxetine within the previous 4 weeks.
• Patients having severe antisocial or borderline personality disorder
• Patients with a past or current diagnosis of schizophrenia, schizoaffective disorder, psychotic disorder, bipolar disorder, or delirium, dementia, or other clinically significant cognitive disorder.
• Patients initiating individual, group, or couple psychotherapy during the three moths prior to study entry (excluding Gambler's Anonymous)
• Patients having prior exposure to acamprosate