In the Netherlands, the policy on care for prisoners who are addicted to opiates is still heterogeneous. The recent guidelines entitled 'Medicinal care for drug addicts in penal institutions' should contribute towards unambiguous and more evidence-based treatment for this group. In addition, it should improve and bring the care pathways within judicial institutions and mainstream healthcare more into line with one another. Each rational course of medicinal treatment will initially be continued in the penal institution. In penal institutions the help on offer is mainly focused on abstinence from illegal drugs while at the same time limiting the damage caused to the health of the individual user. Methadone is regarded at the first choice for maintenance therapy. For patient safety, this is best given in liquid form in sealed cups of 5 mg/ml once daily in the morning. Recently a combination preparation containing buprenorphine and naloxone - a complete opiate antagonist - has become available. On discontinuation of opiate maintenance treatment intensive follow-up care is necessary. During this period there is considerable risk of a potentially lethal overdose. Detoxification should be coupled with psychosocial or medicinal intervention aimed at preventing relapse. Naltrexone is currently the only available opiate antagonist for preventing relapse. In those addicted to opiates, who also take benzodiazepines without any indication, it is strongly recommended that these be reduced and discontinued. This can be achieved by converting the regular dosage into the equivalent in diazepam and then reducing this dosage by a maximum of 25% a week.