The ACL or anterior cruciate ligament is the most important ligament in the knee. When it is completely torn, it can lead to instability or buckling of the knee. There are several options to choose from when selecting a graft for ACL reconstruction such as using autografts including patellar tendon, hamstring tendon, and quadriceps tendon, and allografts (also known as donor tissue or cadaver tissue). Artificial ligaments are also discussed since they are still used in Europe and Asia. This book summarizes the pros and cons of each graft option in detail.