Many patients with arthritis are using alternative modes of therapy, including nutritional supplements, to treat their arthritis. Most patients never tell their doctors that they are taking alternative medications, and few doctors even ask about such activities. Over-the-counter supplements are expensive and consume large amounts of patients' healthcare dollars. Glucosamine has been widely touted as being an effective arthritis treatment. The authors designed and undertook a study to test the efficacy of a polymer of N-acetyl-D-glucosamine (NAG), or POLY-Nag, in a double-blind, placebo-controlled study in patients with osteoarthritis. Results indicate that POLY-Nag may be useful in treating patients with osteoarthritis.