The aim of this study is to evaluate the mid-term results of the Genesis Total Knee Prosthesis, one of the first prostheses with asymmetric shape of the tibial component .The arthroplasty was performed on our patients with retention of the posterior cruciate ligament and, in most of the cases, without replacement of the patella. During the period 1992–1999, 90 patients (116 knees) were operated in our clinic: 81 of them were women and 9 were men with an average age of 68 (52–82) years. The primary indication for the operation was osteoarthritis. 84 patients (109 knees) were evaluated clinically and roentgenographically (Knee Society Knee Score) for a mean time of 98.1 (29.6 – 137.7) months after surgery. There were no infections. (Three) Four of the patients had to undergo a second operation . Two of them, eventually, had their patellae replaced (1,5 and 3 years postoperatively) due to persisting pain of the patellofemoral articulation and lateral patellar subluxation .The other two patients had to undergo revision arthroplasty due to wear of the polyethylene component, one at five years and the other at nine years . Moreover, wear of the polyethylene was also observed on another patient, radiographically, six years after the operation. However, the patient seemed to have no symptoms and was, therefore, unwilling to undergo a revision. The clinical results were satisfactory with a Knee Score of 97(74–100) and Function Score 80 (5–100) .The mean range of motion was 113°(85°–135°). There was no evidence of loosening or any radiolucent lines found radiographically .We consider the results of the Genesis Total Knee Arthroplasty satisfactory .The asymmetric shape of the tibial condyles ensures the fitting of the tibial component. With the exception of cases of severe patella damage, replacement of the patella is not required. The presence of any problems in the patellofemoral articulation is usually connected to the maltracking of the patella or to errors in the surgical technique.