Objectives : To analyze the inclusion criteria of participants, control group interventions, and the results of prior studies of acupuncture for OA. Also to identify aspects of the procedure that are associated with positive outcomes in order to establish ideal acupuncture treatment model. And to assess the methodological quality of the trials with modified Jadad score and FEAS in order to evaluate the quality of prior studies and find out whether or not acupuncture has a positive effect in treating OA. Methods : Articles up to the date of November 2008 were searched via computerized databases of PubMed, Journal of Korean Oriental Medicine, The Journal of Korean Acupuncture & Moxibustion Society and Journal of Oriental Rehabilitation Medicine. Bibliographies of reviewed papers were also searched and reviewed. Only randomized controlled trials (RCTs) and systematic reviews concerning the effects of acupuncture or electroacupuncture (EA) on symptoms of osteoarthritis of the human knee, published in English and Korean were included. The acupuncture treatment methods of the reviewed trials were assessed based on STRICTA. And the methodological quality of the trials was assessed by modified Jadad score and FEAS. Results : Twenty one trials of acupuncture for OA were analyzed. Based on the results of this review the following factors might contribute to optimal results from acupuncture treatment. 1) Usage of $ST_{35}$, $GB_{34$, $EX_{32}$, $ST_{36}$ and $SP_9$ acupuncture points. 2) More than four acupuncture points should be used. 3) More than 15 minutes of needle retention time. 4) Needle length-40mm and diameter-0.30mm 5) Usage of EA 6) more than 10 times treatment 7) Treatment frequency of more than once a week, 8) Treatment duration longer than 6 to 8 weeks. Conclusions : High quality clinical trials of Acupuncture for OA is still in lack. Future investigators must concentrate their attentions on the quality of acupuncture treatment itself used in the trials as well as the methodological quality of trials.