BACKGROUND: Alterations in knee joint kinematics have been suggested as a potential mechanism that influences the development of osteoarthritis of the knee after anterior cruciate ligament reconstruction. Whilst previous work has shown changes in internal-external tibial rotation during level walking, many patients aim to return to high impact activities following surgery. This study examined tibial rotation during single limb hop and drop landings in anterior cruciate ligament reconstructed knees compared to a control group, and also evaluated the influence of graft type (hamstring or patellar tendon). METHODS: In 48 participants (17 patellar tendon graft, 18 hamstring graft and 13 controls) internal-external rotation was measured during single limb hop and drop landings in a gait laboratory at mean of 10 months after surgery. FINDINGS: There was no difference between the two graft types and both patient groups had less internal rotation when compared to the control group. For 60% of patients, internal rotation values were at least 5° less than the control group mean. INTERPRETATION: Anterior cruciate ligament reconstructed knees with both hamstring tendon and patellar tendon grafts show altered rotational kinematic patterns during high impact dynamic load activities.