OBJECTIVE: To investigate the preoperative effects of exercise-based interventions on pain and physical function for people awaiting joint replacement surgery of the hip or knee. DATA SOURCES: Four computer databases (CINAHL, MEDLINE, Embase, and Cochrane Library) were searched until July 4, 2012. Search terms included knee, hip, joint replacement, arthroplasty, physiotherapy, physical therapy, exercise, hydrotherapy, rehabilitation, and preoperative. Reference lists of retrieved articles were also screened. STUDY SELECTION: Randomized or quasi-randomized studies comparing an exercise-based intervention with a no-intervention group for people awaiting hip or knee joint replacement surgery were included. Outcomes were pain and physical function including self-reported function, walking speed, and muscle strength. One of 2 reviewers determined that 18 studies met the inclusion criteria. DATA EXTRACTION: The methodologic quality of each study was independently assessed by 2 reviewers using the PEDro scale, and a final PEDro score was determined by discussion and consensus between the reviewers. Participants' characteristics, content and design of the interventions, and data for quantitative synthesis were extracted by 1 reviewer. DATA SYNTHESIS: For participants awaiting knee replacement surgery, quantitative data synthesis found no significant differences between the exercise and no-intervention groups for pain, self-reported function, walking speed, or muscle strength. For participants awaiting hip replacement surgery, quantitative data synthesis found a significant difference between the groups, with standardized mean differences (SMDs) indicating a medium-sized effect in favor of intervention for both pain (SMD=.45; 95% confidence interval .15-.75) and self-reported function (SMD=.46; 95% confidence interval .20-.72). CONCLUSIONS: Exercise-based interventions can reduce pain and improve physical function for people awaiting hip replacement surgery but not knee replacement surgery.