This article addresses the issue of personal safety of foreigners detained in Polish penitentiary units. In prisons, inter-personal and inter-group relations are crucial for security. The relations of staff with inmates, as well as between inmates and groups of inmates, are of fundamental importance. Specific groups – requiring special behaviour by staff – can include foreigners. The Prison Service has developed procedures for dealing with this category of inmates. In particular, the recognition of the inmates’ environment, the quality of the conduct of penitentiary interventions and the level of intercultural competence of the staff are important for their safety. Crisis situations involving foreigners are also a challenge for the staff.