This study is to evaluate the safety and effectiveness of an injectable slow releasing preparation of naltrexone to reduce alcohol consumption and risk of relapse in alcohol-dependent subjects. Individuals will receive either naltrexone or a placebo injection for a total of three months, with two subsequent followup visits spanning a 6- month period.

Inclusion Criteria:

• Meets criteria for alcohol dependence.
• Abstinent from alcohol for a period of at least 3 days prior to beginning of study.
• Able to read English and complete study evaluations.
• Females who are postmenopausal, have had surgical sterilization, or use reliable means of birth control.

Exclusion Criteria:

• Meets criteria for dependence on a psychoactive substance other than alcohol and nicotine and/or cannabis.
• Prior history of opioid dependence.
• Regular use of psychoactive drugs including anxiolytics and antidepressants.
• Prior treatment with naltrexone.
• Current use of disulfiram.
• Psychotic or otherwise severely psychiatrically disabled (e.g., suicidal, current mania).
• Significant underlying medical conditions such as hepatic, cerebral, renal, thyroid, or cardiac disease.
• Abstinent longer than 28 days prior to randomization.