Agonist therapy (OAT) programs in combination with a psychosocial approach are the most effective way to prevent relapse in opioid-dependent patients. These programs reduce morbidity and risk behaviours for HIV transmission and other infections, improve quality of life and retention in treatment, and have a positive impact on antisocial behaviour. They are therefore very useful for prisoners with a history of opiate use. OATs based on buprenorphine/naloxone (B/N), along with others using methadone, are currently available in Spain. Diversified treatment offers an alternative treatment for opioid dependence that is more personalized and tailored to the patient's characteristics. As regards effectiveness, both drugs are very similar, but B/N shows a better safety profile and fewer drug-drug interactions and can be dispensed in pharmacies once the patient is released, which can assist with the patient' social reintegration. B/N treatment is more expensive than methadone. It is advisable to have different modes of OAT. These should be prescribed according to the characteristics and needs of each case, without incarceration impeding the right to drug treatment, which should be similar to that performed outside prison.