Although many different techniques for opiate detoxification exist, the search continues for more effective approaches to reduce the duration and discomfort associated with opioid withdrawal. It has been shown that very low doses of naltrexone administered in the presence of opiates has analgesic and dependency reducing properties. The purpose of this study is to investigate the effects of very low doses of naltrexone administered during a methadone tapering schedule for opiate detoxification. In addition, this study will compare the effectiveness of two different dose regimens of naltrexone.