Objective To investigate the effectiveness of anterior cruciate ligament (ACL) reconstruction for single bundle rupture using hamstring autograft with preservation of the left bundle. Methods Between March 2005 and May 2009, 20 patientswith ACL single bundle rupture were treated using hamstring autograft with preservation of the left bundle. There were 15 males and 5 females with an average age of 25.5 years (range, 16-43 years). Injury was caused by sports in all the patients. The locations were the left knee in 12 cases and the right knee in 8 cases, including 11 cases of antero-medial bundle rupture and 9 cases of postero-lateral bundle rupture. Ten patients had positive results of anterior drawer test, 8 patients had positive result of Lachman test, and 2 patients had positive results of both tests. The Lysholm score was 67.0 ± 6.2 and International Knee Documentation Committee (IKDC) score was 69.0 ± 7.5. The time from injury to surgery was 1 week to 12 months (mean, 2.8 months). Results All the patients had healing of incision by first intention. Twenty patients were followed up 18.5 months on average (range, 12-36 months). The range of motion of all the knees was more than 130° at last follow-up. The results of both the anterior drawer test and Lachman test were negative in 17patients. The result of anterior drawer test was weakly positive and the result of Lachman test was negative in 2 patients. The result of Lachman test was weakly positive and the result of the anterior drawer test was negative in 1 patient. The Lysholm score and the IKDC score were 91.0 ± 3.7 and 92.0 ± 4.9 at last follow-up, showing significant differences when compared with the preoperative ones (P lt; 0.05). Conclusion ACL reconstruction using hamstring autograft with preservation of the left bundle has satisfactory effects and can partially preserve the proprioceptive sense of the knee, which is beneficial for improving the stability of the knee.