Forty-four of the first 50 knees to undergo anterior cruciate ligament (ACL) reconstruction combined with a valgus tibial osteotomy were reviewed retrospectively at an average of three and a half years later. The combined operation was performed on patients with symptomatic chronic ACL rupture who also had varus malalignment on unilateral weight bearing, usually secondary to a previous medial meniscectomy. All patients originally played regular sports, but before the combined operation, 31 did not play at all. The operation had a low morbidity, and significantly improved clinical symptoms, clinical stability, and functional stability. Postoperatively only one patient could play competitive sports, although a further 26 could play leisure sports. At review there was no radiological progression of osteoarthrosis, and 37 patients (91%) were satisfied or very satisfied with the operation. Performing a valgus tibial osteotomy improved the results of ACL reconstruction in patients with acquired varus malalignment and extended the indications for ACL reconstruction to include patients younger than 40 years of age with early medial compartment osteoarthrosis.