Eleven skeletally immature adolescents underwent anterior cruciate ligament reconstruction using a transphyseal tibial and femoral tunnel. An autologous quadrupled hamstring tendon was used in all cases and the average follow-up was 77.7 months. Clinical results were evaluated using Lysholm knee scores and a return to pre-injury sports activities. Radiological results were evaluated using side-to-side differences of instrumented laxities and growth disturbances compared with the uninjured side on final follow-up orthoroentgenograms. The mean Lysholm score was 97.8 (range 94-100) and mean side-to-side laxity difference was 2.4 mm (range 1-4). Ten of 11 patients returned to pre-injury sports activity. No patient had a leg length discrepancy of over 1 cm or a significant abnormal angular deformity of the knee joint. Therefore, anterior cruciate ligament reconstruction using the transphyseal tunnel and hamstring autograft in skeletally immature adolescents is believed to be a reliable treatment method, which is not associated with significant leg length discrepancy or abnormal angular deformity of the knee joint.