Weight-bearing knee kinematics in patients who received two types of anterior cruciate ligament reconstruction were studied using a fluoroscopy-based three-dimensional measurement technique. Eleven patients with more than 1-year follow-up and good or excellent results participated in this study. Six subjects received anterior cruciate ligament reconstruction using a multiply folded semitendinosus and gracilis tendon graft, and five received combined intra- and extra-articular anterior cruciate ligament reconstruction using the iliotibial tract. The step up/down activity of normal and operated knees was recorded using lateral fluoroscopy. A customized three-dimensional contour model was created from two orthogonal views of each knee and all six degrees of freedom of knee movement were determined using a model matching technique. Both the normal and the reconstructed knees exhibited posterior condylar translation and internal tibial rotation with knee flexion, consistent with previous reports of normal kinematics. There were no statistically significant differences in the axial rotations or lateral or medial condylar anterior/posterior translations between operated and normal knees or between the two groups of operated knees.