Many theoretical analyses today commonly define critical infrastructure as a set of physical and virtual systems and resources that allow society's smooth and stable functioning, and the destruction or damage of that which would endanger the stability or even the security of modern society or the state. The aim of this article is to define the importance of national critical infrastructure from the standpoint of safety, as well as to show some elements of critical infrastructure in Montenegro. This article analyzes the phenomena and processes that have in recent years contributed to the protection of critical infrastructure, threats to critical infrastructure of Montenegro from cyber space, the importance of defining critical infrastructure from the standpoint of the defense system, as well as the importance of the private sector to protect critical infrastructure. Given that Montenegro has not yet defined the critical infrastructure at the national level, the article gives suggestions of steps that need to be implemented in order to define the critical infrastructure in Montenegro.