Twelve studies including 1,248 patients were included in this meta-analysis comparing intra-articular injections of platelet rich plasma (PRP) and intra-articular injection of hyaluronic acid (HA) for the treatment of knee osteoarthritis (OA). Pooled outcomes of interest included clinical outcome, assessed by Western Ontario and McMaster Universities (WOMAC) osteoarthritis index, Knee Injury and Osteoarthritis Outcome Scores (KOOS) and International Knee Documentation Committee (IKDC) scores, and pain assessed by VAS pain scores, WOMAC pain scores and KOOS pain scores. Outcomes were assessed at 6 and 12 months post-treatment. No statistically significant differences in pooled clinical outcomes were observed between the PRP and HA groups at both 6 and 12 months post-operation (p=0.069; p=0.188, respectively). However, pooled pain scores at both 6 and 12 months, were statistically significantly in favour of the PRP group (p=0.001; p=0.001, respectively). Similarly in the subgroup analysis of autologous conditions plasma, pooled pain scores at 6 months were significantly in favour of the autologous conditions plasma group.