Over a three-year period, 40 patients with symptomatic knee OA were randomly assigned to receive a 12-week Tai Chi program or stretching and wellness education program. Outcome measurements were obtained at baseline and on completion of the 12-week program, as well as 24 and 48 week follow-up periods. We compared changes in knee pain, stiffness, and physical function using the well-validated Western Ontario and McMaster Index (WOMAC), as well as clinical knee examination, lower extremity function, knee joint proprioception, and health related quality of life.