30 patients with Kellgren-Lawrence grade II-III knee osteoarthritis were randomized to receive three weekly intra-articular injections of either leukocyte-poor platelet rich plasma (LP-PRP) autologous conditioned plasma or placebo saline. The purpose of this study was to determine if LP-PRP administration demonstrated efficacy for improvement in pain, stiffness, and function on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) compared to placebo, without an increased risk of adverse events. The results demonstrated significant improvement in WOMAC pain, stiffness, and function scores relative to baseline throughout follow-up to 12 months, with significant differences in scores between groups in favour of the LP-PRP group. No adverse events were reported in the LP-PRP group.