Osteoarthritis (OA) is currently defined by the American College of Rheumatology as a "heterogeneous group of conditions that leads to joint symptoms and signs which are associated with defective integrity of articular cartilage, in addition to related changes in the underlying bone at the joint margins." Its prevalence after the age of 65 years is about 60% in men and 70% in women. The etiology of OA is multifactorial, with inflammatory, metabolic, and mechanical causes. A number of environmental risk factors, such as obesity, occupation, and trauma, may initiate various pathological pathways. OA indicates the degeneration of articular cartilage together with changes in subchondral bone and mild intraarticular inflammation. The principal treatment objectives are to control pain adequately, improve function, and reduce disability. Acetaminophen is frequently used for symptomatic OA with mild to moderate pain. Nonsteroidal antiinflammatory drugs (NSAIDs) are more effective in the case of moderate-severe pain, but they have an increased risk of serious upper gastrointestinal adverse events. The newer cyclooxygenase COX-2 specific inhibitors (Coxibs) are as efficacious as traditional NSAIDs and have a better gastrointestinal safety profile. Other compounds (eg, chondroitin sulfate, diacerein, glucosamine sulfate) have a symptomatic effect that is slower and less than that of NSAIDs. The structure-modifying effects of drugs are currently being evaluated, and both glucosamine sulfate and diacerein have been shown in some trials to have a beneficial structural effect. Nonpharmacological interventions are frequently and widely used in the management of OA patients, but there is little evidence that they are effective: the best studied and most successful nonpharmacological interventions are patient education, self-management, and exercise. There is some evidence for the pain-relieving efficacy of thermotherapy and transcutaneous electrical nerve stimulation (TENS) but not of electrotherapy, acupuncture, homeopathy, or manual therapy. The value of interventions aimed at improving function and maximizing independence (occupational therapy, walking aids, workplace adaptation) is also unclear. The disease course and patient's requirements often change over time, thus requiring a periodic review and readjustment of therapy rather than the rigid continuation of a single treatment.