Anterior cruciate ligament (ACL) injury is one of the most common and disabling injuries amongst sports players. Despite the great attention paid to the topic by scientific literature, almost half of players affected by an ACL injury do not return to the same functional levels they had prior to the injury. This fact appears to be closely related to the appropriateness of the rehabilitation protocol used. Hence, it is of fundamental importance for the physiotherapist to know what the main goals to pursue are in the early post-injury and post-surgery phases, as well as the criteria for establishing whether or not surgery is advisable. It is also important for the physiotherapist to know what the characteristics of the grafts used in ligament reconstruction are, and what are the most common complications and the best strategies for addressing them.