• A multiclinic controlled trial of naltrexone in opiate-dependent persons led to these conclusions: (1) a narcotic antagonist is an acceptable treatment for a small number of patients undergoing treatment for opiate dependence; (2) the group most likely to be candidates for such treatment are those who are relatively opiate-free ("post-addicts") and well motivated to seek treatment; (3) although differences between patients treated with placebo and naltrexone were slight, both retention in treatment and opiate-free urine tests favored the naltrexone group; (4) adverse effects of relatively short-term treatment were slight, largely being symptoms and signs of precipitated abstinence in patients with residual dependence.