This paper describes the ventilation system used in underground hard rock mines in Sweden and Finland, which differs in many respects from the system commonly used in other major mining countries such as Australia, Canada, South Africa, and the USA. The Nordic system utilizes auxiliary fans with a variable speed drive to distribute primary airflow to working levels instead of regulators, which are commonly used in other countries. In addition to comparing the Nordic system with the system used in other countries, this paper describes the system's ventilation-on-demand and air conditioning, as well as ventilation regulations in Sweden and Finland. A discussion regarding the potential to use natural-assisted refrigeration in the future is also described in this paper.