English-language articles were included if the articles described randomized, controlled trials of the effects of needle or electroacupuncture (EA) on symptoms of osteoarthritis of the knee. Articles were excluded if they described case studies, unblinded, nonrandomized, or noncontrolled trials; used types of acupuncture other than needle or EA (such as bee venom acupuncture); studied types of arthritis other than osteoarthritis (such as rheumatoid); studied joints other than the knee; or were unavailable in English.