The purpose of this study was to assess ultrasonographic image changes in the patellar tendon after removal of its central one third for anterior cruciate ligament reconstruction. Fourteen patellar tendons in 14 patients were assessed preoperatively and at 2 weeks, 4 weeks, 2 months, 6 months, and 12 months postoperatively. With time, the entire donor tendon became enlarged, hypoechoic, and inhomogeneous compared with the presurgical state. Tendons enlarged maximally in anteroposterior thickness by 2 months and then began to diminish, remaining two times their original anteroposterior thickness by 12 months and never returning to their preoperative appearance. The margins of the defect became indistinct over time. In the donor patellar tendon, abnormal echogenicity was profound and persisted up to 1 year after surgery. Ultrasonographic imaging has the ability to evaluate the postoperative patellar tendon over time and to monitor the normal changes seen with healing.