Rehabilitation following anterior cruciate ligament reconstruction is a subject of controversy in the orthopaedic and rehabilitation literature. With an increasing number of these operations currently being performed and with the advent of arthroscopically assisted ACL reconstruction over the past several years, particular rehabilitation needs and problems have been identified in association with these patients. Various authors have stressed one or a combination of a few basic themes which outline the basic rehabilitation concerns following ACL reconstruction. The most fundamental concern is the need to initiate motion very soon after surgery. Prolonged postoperative immobilisation is known to cause serious complications after ACL reconstruction which can be avoided by early motion. Positions or activities which may apply excessive stress to a newly reconstructed ACL must also be considered. The amount of protection required by the graft will vary depending upon the type of graft used and the quality of fixation obtained intraoperatively. Most authors agree that nonweightbearing, active resistive quadriceps exercises should be avoided for an extended period, while closed chain exercises may be initiated much earlier. Strength recovery is obviously important for the quadriceps postoperatively, but maximal strength returns of all of the muscles about the knee must be pursued. Hamstring strength is of particular concern as this may provide an active support to the reconstructed ACL. Sensory loss in the knee after ACL disruption should also be addressed during rehabilitation, prior to a patient's return to full athletic activity. Progressive neuromuscular re-education exercises which rely on sensory input from intact pericapsular structures are encouraged. A final concern is the role of bracing after ACL reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)