Anterior cruciate ligament (ACL) deficiency can result in symptomatic functional instability of the knee regardless of the patient's age. We reviewed a single surgeon database of 908 ACL reconstructions carried out in the last 20 years for symptomatic instability. 14 patients were identified who were 55 years or above at surgery (mean: 60 years, range 55-75 years). Patients were evaluated clinically and with clinical outcome scoring and KT-1000 arthrometry assessment. 12 patients (86%) were available to attend for follow-up at a mean 9 years after ACL reconstruction. The median pre-injury Tegner score was 5.5 (range 1-7) and the median pre-operative Lysholm score was 33 (range 15-67). Initially, one patient had a good result but subsequently the patient undergone total knee replacement 5 years after ACL reconstruction. For the remainder, at the most recent review, the median Lysholm score had improved to 79 (range 43-100, P < 0.05) although it had deteriorated from the maximum achieved post-op score of 85.5 (range 53-100, P < 0.05); and the Tegner score had declined to 3 (range 1-5, P < 0.05). KT-1000 testing demonstrated a mean side-to-side difference improvement in laxity from 4.6 +/- 1.3 mm (range 3-7) to 1.5 +/- 1.2 mm (range 0-4, P < 0.05) and >2 mm difference in only one knee (for which it was known that the graft had failed at 11 years after ACL reconstruction). At review, the same knee was the only one that demonstrated a pivot shift. ACL reconstruction with autograft in the above-55 patient with minimal osteoarthritis is a safe procedure that returns stability to the knee and permits a return to a reasonable level of activity.