At present, there are no international standards available for design and testing of isolation rooms in health-care facilities. Standardization regarding airborne infection (negative pressure) isolation rooms is an important task not only for improving public health across national boundaries, but also for controlling health care costs, as isolation room suites often require considerable resources to construct and maintain. An important step in moving toward international standardization is to come to a consensus about what exactly is proper and adequate function in a negative-pressure isolation room. In this report we examine current and best practice in design and performance testing of negative pressure isolation rooms in Nordic hospitals. Design considerations and performance monitoring tests for isolation rooms are discussed. Nordic, European and other national existing guidelines and standards are examined. Current practice in design and testing of isolation rooms in Nordic hospitals is described, based on information obtained from building engineering and health care professionals in over 20 hospitals in Norway, Sweden, Denmark and Finland. Finally, best practice is identified based in part on the review of current and pertinent guidelines, standards, and regulations; in part based on an evaluation of the scientific evidence behind these guidelines, standards and regulations; and in part based on our review of current practice in Nordic hospitals.