22 randomized controlled trials were included in this meta-analysis investigating the efficacy of intra-articular hyaluronic acid injections in the treatment of knee osteoarthritis. Data was extracted from identified studies for outcomes of pain at rest, pain during activity, and functional measures, and pooled at 4 different time intervals: 2-6 weeks, 10-14 weeks, 22-30 weeks, and 44-60 weeks. Analysis of all studies demonstrated significant effects of hyaluronic acid injections at 2-6weeks for pain at rest, and 10-14 weeks and 22-30 weeks for pain during activity. No significant effect was observed for functional measures. Sensitivity analysis of only high-quality studies demonstrated no significant effect of hyaluronic acid for any outcome at 2-6 weeks or 10-14 weeks.