PURPOSE: People with knee osteoarthritis (OA) report ongoing limitations in climbing stairs, even after total knee arthroplasty (TKA). The aim of this systematic review was to synthesise the available evidence of factors affecting stair climbing ability in patients with knee OA before and after TKA. METHOD: A systematic search was conducted of common electronic databases. All English language abstracts where stair-climbing was assessed in patients with either knee OA or at least 6 months after TKA, and a relationship to any physical, psychological or demographic factors was reported. RESULTS: Thirteen studies were included in the final review, nine investigated a knee OA population, and four investigated a TKA population. For patients with knee OA there was consistent and convincing evidence that greater stair-climbing ability was related to stronger lower limb muscles and less knee pain. For patients with TKA there was much less research, and no conclusions could be reached. CONCLUSIONS: For people with knee OA there is evidence that some physical, demographic and psychosocial factors are related to stair-climbing ability. However, the evidence for similar relationships in the TKA population is scarce and needs more extensive research. Implications for Rehabilitation People with knee osteoarthritis experience difficulty when climbing stairs, and this remains challenging even after knee replacement. For people with knee osteoarthritis, a range of physical, demographic and psychosocial factors contribute to stair-climbing ability, however, evidence for similar relationships in the TKA population is scarce. Rehabilitation that is multi-faceted may be the best approach to improve stair-climbing in people with knee osteoarthritis.