This paper reports results from the first controlled trial of opioid withdrawal treatment in the UK using lofexidine in a prison setting. Seventy-four opioid dependent male inmates at a Southern England prison were randomised to receive either methadone (the standard prison treatment) or lofexidine using a randomised double-blind design. No significant statistical difference between the treatment groups was found in relation to the primary variable of severity of withdrawal symptoms (effect size = 0.12). No discernible difference was found in the sitting blood pressure or heart rate of the two groups during the trial. These results provide support for the use of lofexidine for the management of opioid detoxification in the prison setting. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.