There is a great deal of interest in the use of naltrexone as a treatment for alcohol (ethanol) dependence since there is a rapidly expanding body of evidence to support its efficacy and tolerability in this indication. Naltrexone, a long-acting, nonselective opioid receptor antagonist has been shown to reduce alcohol intake when combined with behavioural treatment. Naltrexone may prevent the return to clinically significant drinking by blocking the pleasurable effects or "high' associated with alcohol drinking. Results from controlled studies showed that in alcohol dependent patients taking naltrexone 50 mg/day in combination with behavioural treatment, relapse rates were reduced by 50% compared with placebo treated patients. Historically, several factors have limited the use of effective pharmacological adjuncts in the treatment of alcohol dependence. These include safety considerations in this vulnerable population, and the fact that some treatment programmes discourage alcohol-dependent patients from taking medications. The most common adverse effects reported with the use of naltrexone at a dosage of 50 mg/day include nausea and vomiting. Naltrexone does not appear to be hepatotoxic in dosages recommended in the treatment of alcohol dependence, i.e. 50 mg/day. Thus, naltrexone appears to offer significant therapeutic benefits at a relatively low risk, when used judiciously and with behavioural treatment for alcohol dependent patients.