Fifty magnetic resonance (MR) imaging examinations were performed in 37 patients after arthroscopic anterior cruciate ligament (ACL) reconstruction with patellar bone-tendon-tibial bone autografts. T1-weighted sagittal and axial images were obtained. In 34 patients with clinically stable ACL autografts, 43 of 47 MR examinations demonstrated a well-defined, intact ACL autograft. All three patients with ACL laxity failed to demonstrate a well-defined autograft, for an overall correlation between MR imaging and clinical examination results of 92%. Of the 12 patients who underwent second-look arthroscopy, 100% correlation was present between MR imaging and arthroscopic results. As in the nonreconstructed knee, buckling of the posterior cruciate ligament was suggestive of ACL laxity. MR imaging also documented optimum placement of bone tunnels in the femur and tibia. MR imaging has proved to be an excellent noninvasive imaging modality for evaluating ACL reconstruction, while also providing ancillary information about the postoperative knee.