In countries where prison healthcare is truly independent and the principle of equivalence is fully respected, advance directives are a means of increasing patients' self-determination. Problems persist in prisons, similar to those existing outside the prison context, as regards a patient's ability to anticipate the medical and other details of a future situation in which he or she becomes incompetent. This chapter first examines general ethical and legal aspects of advance directives in the context of imprisonment and then discusses advance directives in three specific situations, hunger strikes, end-of-life care and psychiatric treatment of detained persons.