[Purpose] To compare outcomes of anterior cruciate ligament (ACL) reconstruction after open kinetic chain (OKC) exercises and closed kinetic chain (CKC) exercises. [Subjects and Methods] The subjects comprised 11 female and 47 male patients who are randomly divided into two groups: which performed a CKC exercise program Group I and Group II which performed an OKC exercise program. Pain intensity was evaluated using visual analogue scale (VAS). Knee flexion was evaluated using a universal goniometer, and thigh circumference measurements were taken with a tape measure at baseline and at 3 months and 6 months after the treatment. Lysholm scores were used to assess knee function. [Results] There were no significant differences between the two groups at baseline. Within each group, VAS values and knee flexion were improved after the surgery. These improvements were significantly higher in the CKC group than in the OKC group. There were increases in thigh circumference difference at the 3 and 6 month assessments post-surgery. A greater improvement in the Lysholm score was observed in the CKC group at 6 months. [Conclusion] The CKC exercise program was more effective than OKC in improving the knee functions of patients with ACL reconstruction.