Active magnetic bearings present unique capabilities compared to other bearing systems, allowing their use in a range of challenging environments and applications. This paper reviews these unique capabilities, which can be broadly categorized as:elimination of wear;elimination of sealing and lubrication systems;reduction or elimination of transmitted noise and force; use as instrumentation systems; and thermal capabilities. When combined, these capabilities can provide high reliability and availability in challenging applications. The paper goes on to consider how a challenging application or environment may affect the design of a magnetic bearing system and the use of these capabilities. Examples of such applications within the authors own company are presented together with a brief review of some of the available literature.