The purpose of this paper is to provide guidance for Canadian hospital medical directors in planning the provision of protection for their patients and staff against gamma radiation hazard from nuclear war. The implications of the distribution of fallout in Canada are that the probability of exposures in excess of 600 r in the period “96 hours after fallout” is high in Southern Ontario and Quebec but low in the western provinces and in the North. All hospitals should have a shielding capacity; for many, this will entail structural alterations. The aim would be to provide a protective factor of 100 or better, together with necessary standards of habitability. The engineering significance of the recommendations is discussed.