- Studies have found that naltrexone, a long-acting opiate antagonist, owing to poor patient compliance, is of limited value in preventing relapse. The current study investigates compliance with a 9-month course of naltrexone (25–50 mg daily) given with counseling after ultra-rapid opiate detoxification which uses clonidine and naltrexone under general anesthesia. Eighty-three of 113 randomly selected patients (out of 640), who were detoxified more than 1 year prior (average 1.5 years), responded to phone interviews. Phone questionnaire asked about patients' compliance with naltrexone, counseling and drug use since detoxification. Similar interviews were also conducted with patients' significant other. Non-relapse patients (n=47, 57%) took naltrexone an average of 2 months longer than did relapse patients (n=36, 43%). About half of the non-relapse patients completed at least 5 months of naltrexone, 30% completed at least 7 months and about 20% completed 9 months. Fifty-five percent of the relapse patients stopped using naltrexone by the end of the 3rd month, and by the end of 7th month 10% continued to take it. After the first 2 months the decline in naltrexone compliance was about the same for relapse and non-relapse patients. These results are more encouraging about the use of naltrexone for relapse prevention than previous studies. This method of using naltrexone should be further tested in prospective random assignment controlled studies.