As so-called second-generation power reactors are approaching the end of their original design lives, assessments are being made to determine the feasibility and economics of extending plant life. Although components exposed to neutron and gamma irradiation are often those of most concern in terms of in-service ageing and continued fitness for service, ageing of out-of-core components can also limit the possibility of extended service life beyond design life. In CANDU®reactors, life extension decisions occur when the Zr-2.5Nb pressure tubes reach end of life, typically after about 25 years of service for the first CANDU-6 units. At the time of pressure tube replacements, the remaining life predictions for several other major components or systems provide the information required to determine life extension feasibility. Several CANDU reactors are currently being refurbished, with others planned, and experience to date shows that the steam generators, heat transport system piping and various balance of plant piping systems are typically those requiring careful assessment to ensure successful refurbishment. In this paper, we discuss AECL R&D that is oriented towards providing the chemistry and materials inputs required to assess current condition and predict future ageing of CANDU reactor out-of-core components and systems, and in particular steam generators (Alloy 800 tubing and carbon steel internals), feeder pipes and related heat transport system piping (carbon steel flow accelerated corrosion, feeder cracking). Systems and components that may impact future life will also be discussed, along with the related R&D, and this includes balance of plant system piping (feedwater piping and buried piping), cables and concrete structures.