OBJECTIVE:The primary aim was to evaluate the effect of a dosed walking program on knee pain for patients with severe knee osteoarthritis (OA). Secondary aims evaluated the effects on cardiovascular health, function and quality of life. DESIGN:Participants with severe knee OA and increased cardiovascular risk were randomly assigned to a 12-week walking program of 70 min/week of at least moderate intensity, or to usual care. The primary outcome was knee pain (0-10). Secondary outcomes were of cardiovascular risk including physical activity, blood pressure, blood lipid and glucose levels, body mass index and waist circumference; WOMAC Index scores; physical function; and quality of life. RESULTS:Forty-six participants (23 each group) were recruited. Sixteen participants (70%) adhered to the walking program. Intention to treat analysis showed no between-group difference in knee pain. The walking group had increased odds of achieving a healthy systolic blood pressure (OR = 5.7, 95% CI 1.2-26.9), and a faster walking speed (Mean Difference (MD) = 0.12 m/s, 95% CI 0.02-0.23). Per protocol analysis based on participant adherence showed the walking group had more daily steps (MD = 1345 steps, 95% CI 365-2325); more time walking (MD = 18 min/day, 95% CI 5-31); reduced waist circumference (MD = -5.3 cm, 95% CI -10.5 to -0.03); and increased knee stiffness (MD = 0.9 units, 95% CI 0.07-1.8). CONCLUSIONS:Patients with severe knee OA prescribed a 12-week walking program of 70 min/week may have had cardiovascular benefits without decreasing knee pain. Australian New Zealand Clinical Trials Registry ACTRN12615000015549.