Intra-articular injections of hyaluronic acid products may eliminate pain, improve mobility and quality of life, and delay osteoarthritis progression. In this study, we evaluated the safety and efficacy of sodium hyaluronate injections given after knee arthroscopy. Forty-six patients with early osteoarthritis and a symptomatic meniscus tear were prospectively randomized into study (injection) and control groups and underwent knee arthroscopy. Study patients received 3 sodium hyaluronate injections after surgery. Study and control outcomes were compared 3 and 6 months after surgery. The injection patients had significantly less pain (visual analog scale) at 3-month follow-up and more flexion at 6-month follow-up. Tenderness, pain on motion, and crepitus were significantly more likely to be absent from injection patients at the 3- and 6-month follow-ups. Patients with osteoarthritis and a symptomatic meniscus tear may experience more pain relief and functional mobility after arthroscopic surgery plus hyaluronic acid injections than after arthroscopy alone.