Sixty patients with primary knee osteoarthritis were randomized to receive intra-articular ozone therapy at 40 µg/mL (n=20), 20 µg/mL (n=20), or oxygen as control (n=20). The primary outcome was pain reduction, measured by the Visual Analog Scale (VAS) and WOMAC pain subscale. Secondary outcomes included functional mobility (WOMAC function, FROM, TUG, and 6MWT). Outcomes were evaluated at baseline, two weeks, one month, and two months post-intervention. Overall, both ozone groups showed significantly greater reductions in pain and improvements in function compared to the control, with no significant differences between the two ozone concentrations. The findings suggest that both ozone doses are effective, with 20 µg/mL offering similar benefits to 40 µg/mL, potentially optimizing safety and cost.