The determination of all significant contributing factors to the risks arising from a facility or activity is seen as the main objective of Probabilistic Safety Assessment (PSA). The results of PSA serve as a base for the safety-related decision-making process and the understanding that the complete risk profile is essential to priority, effectiveness and even the adequateness of the safety-related decisions. Eventually, the complete risk profile of nuclear facility requires aggregation of risk, which implies a combined representation of risk across the various contributors. This paper describes ongoing IAEA efforts aimed to provide a general methodology for aggregation of various risk contributors for nuclear facilities. The discussion on risk aggregation is presented from different perspectives, covering such aspects as different groups of hazards (internal and external), different operational states and multi-source considerations.