Osteoarthritis (OA) is the most common form of chronic arthritis worldwide. The etiology of pain in osteoarthritis is multifactoral, and includes mechanical and inflammatory processes. The use of intra-articular viscosupplementation in the nonoperative management of patients with osteoarthritis has become quite popular. Recent clinical data have demonstrated that the anti-inflammatory and chondroprotective actions of hyaluronic acid viscosupplementation reduce pain, from 4 to 14 weeks after injection, while improving patient function. Viscosupplements are comparable in efficacy to systemic forms of active intervention, with more local reactions but fewer systemic adverse events, and hyaluronic acid has more prolonged effects than IA corticosteroids. Although several randomized controlled trials have established the efficacy of this treatment modality, additional high quality randomized control studies with appropriate comparison are still required to clearly define the role of intra-articular hyaluronic acid injections in the treatment of osteoarthritis. We review the basic science and development of viscosupplementation and discuss the mounting evidence in support of its efficacy and safety profile.