['To observe the therapeutic effect of acupuncture combined with blood-letting therapy for knee osteoarthritis (KOA) and to analyze the synergism of the blood-letting therapy.', 'Sixty-three cases of KOA patients were randomized into a treatment group (n=31) and a control group (n=32). Patients of treatment group were treated with routine acupuncture at Ashi-points, Dubi (ST 35) and Neixiyan (EX-LE 4), Zusanli (ST 36), Yanglingquan (GB 34), etc. on the affected side, 3 times a week for 4 weeks, in combination with blood-letting (at the superficial veins around popliteal fossa) once a week for 4 weeks. Patients of control group were treated with routine acupuncture only. Western Ontario and McMaster Universities osteoarthritis index scores (WOMAC) and clinical therapeutic effects served as the objective indexes for evaluating the efficacy of blood-letting therapy.', 'After the treatment, of the 32 and 31 KOA patients in control and treatment groups, 4 (12.50%) and 5 (16. 13) were under control in their symptoms, 14 (43.75%) and 17(54.84%) experienced marked improvement, 10 (31.25%) and 6 (19.35%) had an improvement, and 4 (12.50%) and 3 (9.68%) were failed, with the total effective rates being 87.50% and 90.32% respectively. No significant difference was found between the two groups in the therapeutic effect (P > 0.05). In comparison with pre-treatment, WOMAC scores, pain index, and physiological integral scores in treatment and control groups after the first and the last treatment decreased significantly (P < 0.001), and their joint stiffness index of the last treatment also lowered considerably (P < 0.001). The difference values of the integral scores between post- and pre-treatment in WOMAC, pain index, and physiological function of treatment group were remarkably higher than those of control group (P < 0.05).'] Does [ Randomized controlled clinical trail on treatment of knee osteoarthritis with acupuncture combined with blood-letting therapy ]?