Risk Breakdown Structure (RBS) is a hierarchically organized depiction of project risks into categories and sub-categories. In an RBS, risks are organized and structured in such a way to provide a standard presentation of project risks that facilitates understanding, communication and management.

It looks very similar to the Work Breakdown Structure (WBS), but both serve different purposes in a project. As with WBS, RBS also starts with major risk categories and then decomposes them into more detailed ones. RBS reminds participants in the risk identification process of the many sources from which risks may arise. Each descending level in a risk breakdown structure represents an increasingly detailed definition of sources of risk to the project.

A very simple Risk Breakdown Structure is shown below to illustrate the concept. In a real project, the RBS will have many more elements.