Osteoarthritis (OA) is a common, painful, and debilitating condition that affects approximately 46.4 million individuals in the United States. By 2012, this number is expected to increase to 60 million. In addition, it is the leading cause of activity limitation in adults and represents a widely acknowledged economic burden. Although the ultimate goal is to slow or prevent OA progression, at present, medical management of OA is aimed primarily at controlling symptoms of pain and stiffness and maintaining joint mobility and quality of life. Because of the lack or perceived lack of response to many conventional therapies for OA as well as concerns regarding the long-term administration of drugs (eg, nonsteroidal anti-inflammatory drugs), oral joint health supplements (OJHSs) have become increasingly popular among patients with OA. This article briefly reviews pertinent molecular mechanisms involved in the development of OA and summarizes available in vitro and in vivo evidence supporting the use of avocado and soybean unsaponifiables (ASU) either alone or in combination with glucosamine and chondroitin sulfate in patients with OA. Basic scientific research studies and a systematic review and meta-analysis of the available high-quality randomized clinical trials indicate that 300 mg of ASU per day (with or without glucosamine and chondroitin sulfate) appears to be beneficial for patients with hip or knee OA. There is also some evidence that ASU or ASU/glucosamine/chondroitin sulfate combination products could be used prophylactically in even the earliest stages of OA. Considering concerns regarding inferior-quality OJHSs, consumers and physicians are encouraged to take an evidence-based approach when evaluating OJHSs to identify and recommend safe and effective products that meet label claims when tested independently, and are of the highest quality.