This article provides a profile of prisoners who had entered the drug detoxification programme in Mountjoy Prison up to February 1999. A total of 187 prisoners entered the programme of whom 173 successfully completed it. A profile of those attending the programme, based on addiction assessment form completed prior to commencement, is provided. This profile contains information on the social and employment background of patients, and their forensic and drug-taking history. The results of the programme's first 12 month review, based on 86 prisoners who had completed the programme found that 56 of this total had relapsed giving a 12 relapse rate, when those who could not be followed up were included, of 78%. This compare favourably to inpatient detox programmes internationally which have an average of 90% relapse rate. The author concludes that, as a only a small percentage of people will ever retain a drug free life once they have become opiate addicted, people should not have to choose between detoxification and no treatment at all. Methadone treatment would be a suitable approach for a number of those who had relapsed after the detoxification programme and should be this should be available to prisoners.