Despite changes in rehabilitation protocols, an extension deficit remains an important potential cause of significant morbidity following anterior cruciate ligament (ACL) reconstruction. An extension-assisting brace was designed using a limited motion brace and an elastic strap across a fulcrum on the anterior aspect of the knee joint. The effects of the brace were investigated in 40 patients undergoing primary ACL reconstruction using an autogenous central third patellar tendon graft. The patients were randomized either to use the brace in the first 6 weeks postoperatively or to undertake the same accelerated rehabilitation programme but without any brace, and they were reviewed at 4 months postoperatively. The following data were recorded: passive and active extension and flexion deficits compared with the non-operated limb. KT-1000 assessment of anterior laxity and isometric quadriceps and hamstring strength. There was no difference between the two groups for any of the recorded variables. This was largely attributed to satisfactory tunnel placement and emphasis on the restoration of extension and quadriceps function during the early postoperative rehabilitation.