We report our experience using the Leeds-Keio artificial ligament for anterior cruciate ligament (ACL) reconstruction. The study relates the results of the first 40 patients subjected to arthroscopic reconstruction of the ACL with a Leeds-Keio ligament, with a mean follow-up of 73 months. No associated peripheral procedures were carried out on any patient. The average age of the patients at the time of the operation was 31 years (range 26-35 years). The rehabilitation protocol followed by all patients aimed at resumption of sport 4 months after the operation. Clinical assessment included IKDC and the Lysholm scoring scale. The KT-2000 system was used for instrumented evaluation of joint laxity. All patients underwent a radiographic check-up. Clinically there were 55% excellent or good results when using the IKDC scale, while with the Lysholm score, satisfactory results were obtained in 80%. Complete post-traumatic rupture of the ligament was observed in three patients. No patient suffered an episode of either hydrarthrosis or reactive synovitis, which indicates good tolerance to the ligament. The radiographic evaluation of the operated knees showed a close correlation between the appearance of degenerative phenomena and performance of arthroscopic meniscectomy. The results achieved with the Leeds-Keio artificial ligament 5 years after application, although not completely satisfactory and inferior to those obtained with autologous biological ligaments, should be considered an encouragement to promote new efforts in this interesting research field.