The American College of Rheumatology (ACR) recently provided an update to the guidelines published in 1995 on the management of osteoarthritis (OA) of the knee and hip. Members of the Ad Hoc Committee on OA Guidelines followed an evidence-based medicine approach to revise the guidelines by reviewing an extensive literature search of the Cochrane and Medline databases and published abstracts, and discussing evidence with expert rheumatologists. The goal of the guidelines is to provide recommendations to control patients' OA pain, improve function and health-related quality of life, and avoid therapeutic toxicity. As in the original guidelines, nonpharmacologic interventions involving patient education and physical measures are recommended following initial diagnosis of OA. The pharmacologic algorithm was updated to include currently available therapeutic agents. Acetaminophen remains first-line therapy because of its cost, efficacy, and safety profiles. Cyclooxygenase-2-selective inhibitors (coxibs) have been included as an alternative to nonselective nonsteroidal anti-inflammatory drugs (NSAIDs) in patients at risk for upper gastrointestinal adverse events. Tramadol is an available alternative for patients who have a contraindication to coxibs or nonselective NSAIDs or for those who have not responded to previous oral therapy. Intra-articular injections or topical therapy may be used as monotherapy, or as an adjunct to oral analgesia. Surgical treatment of OA remains a last resort for patients who have failed to respond to nonpharmacologic and pharmacologic treatment approaches, and have progressive limitation in their activities of daily living. Several therapies for the prevention or treatment of OA are currently under investigation, including nutritional supplements, such as glucosamine and chondroitin, disease-modifying OA drugs, and devices, such as acupuncture and electromagnetic therapy. It is anticipated that the guidelines for the management of OA will continue to evolve as new therapies become available.