en Orthopedic Surgery Orthopedic Surgery Original Research Original Research <p> <strong> Background </strong>:Disruption of anterior cruciate ligament (ACL) is a common ligamentous injury of the knee. The choice of graft for (ACL) reconstruction remains controversial. This prospective, randomized clinical trial aimed to compare clinical results of bone-patellar tendon-bone (BPTB) grafts and four-strand semitendinosus-gracilis (ST) grafts for ACL reconstruction over a 3-year follow-up interval. </p><p> <strong> Methods </strong>:Seventy-one patients with an average age of 29± 4.5yearswere treated for torn ACL between 2008 and 2009. Forty-sixpatients underwent reconstruction with BPTBautograft, and 41 were treated with STautograft.At the time of final follow-up, 37 patients in patella group and 34 patients in hamstring group were evaluated in terms of return to pre-injury activity level, pain, knee stability, range of motion,IKDC (International Knee Documentation Committee) score and complications. </p><p> <strong> Results </strong>: At 36thmonth of follow-up, 34 (92%) and 28 (82%) patients in BPTB and ST group, respectively had good-to-excellent IKDC score (p > 0.05). Theactivity levelswerehigher in BPTB group(p> 0.05). At 3rd yearof follow up, the Lachman test was graded normal, for 23 (62%) and 11 (32%) patientsin BPTB and ST group, respectively(p=0.019).Regarding the pivot-shift test, 29 (79%) and 15 (44%) patients in patella and hamstring group, respectively had normal test at the latest follow-up (p=0.021).There were no significant differences in terms of thigh circumference difference, effusion, knee range of motion, pain and complications. </p><p> <strong> Conclusion </strong>: Theresults indicate a trend toward increased graft laxityand pivot-shift grades in patients undergoing reconstruction with hamstring autograft compared with patella tendon. However, the two groups had comparable results in terms of activity level and knee function. </p><p>  </p> Anterior Cruciate Ligament (ACL), Reconstruction, Bone-Patellar Tendon-Bone (BPTB) graft, Semitendinosus-gracilis graft, Outcome. 903 910 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-1569-16&slc_lang=en&sid=1 Mohammad Razi m_razi@yahoo.com 200319475328460014004 200319475328460014004 No Department of Orthopedics and Sport Medicine, RassoleAkram Hospital, Iran University of Medical Sciences, Tehran, Iran. Mohammad Mahdi Sarzaeem mmsarzaeem@yahoo.com 200319475328460014005 200319475328460014005 Yes Department of Orthopedic Surgery, Imam Hossein Hospital, ShahidBeheshti University of Medical Sciences, Tehran, Iran. Gholam Hossein Kazemian gh_kazemian@yahoo.com 200319475328460014006 200319475328460014006 No Department of Orthopedic Surgery, Imam Hossein Hospital, ShahidBeheshti University of Medical Sciences, Tehran, Iran. Farideh Najafi faridehnajafi1@gmail.com 200319475328460014007 200319475328460014007 No Department of Orthopedic Surgery, Imam Hossein Hospital, ShahidBeheshti University of Medical Sciences, Tehran, Iran. Mohammad Amin Najafi najafi.ma@yahoo.com 200319475328460014008 200319475328460014008 No Faculty of Medicine, Isfahan University of Medical Sciences, Esfahan, Iran.