In Europe, irregular migrants and rejected asylum-seekers still face detention. This chapter examines the most important aspects related to health in the context of immigration detention in Europe. Reviewing the literature and drawing on field evidence from IOM projects, it identifies the main health conditions of migrants in detention and looks into the common EU standards set in the Return Directive and the Reception Condition Directive as well as the relevant non-binding resolutions of the Council of Europe. The main finding is that despite these policies being in place, conditions typically found in European migrant detention facilities pose risks both to the physical and mental health of migrants as well as to immigration officials and health professionals working with detainees. Health conditions in detention facilities need to be improved by avoiding over-crowding and prison-like conditions as well as training staff to the specific requirements of immigration detention.