Thirteen semiconstrained total knee arthroplasties (TKA) were performed in nine men with classic hemophilia. The average age at surgery was 38 years, the average Factor VIII administration during hospitalization was 84.222 units, and the average hospitalization time was 33 days. Four patients (44%) died during the observation period, three from acquired immunodeficiency syndrome (AIDS) contracted through contaminated Factor VIII plasma concentrates and one from sudden cardiac arrest. One of the patients who died from AIDS had a positive test for human immunodeficiency virus (HIV) at surgery. He died three months after the arthroplasty. The remaining two patients contracted AIDS one year and four years after the arthroplasty. All but one patient were followed for at least one year, with an average follow-up period of 43 months. Using The Hospital for Special Surgery Knee Rating Scale, the overall result was excellent in nine knees and good in three knees. All patients were completely relieved of pain. TKA in hemophiliacs is an effective treatment for otherwise intractable chronic knee pain due to severe joint degeneration. However, caution should be taken in HIV-positive patients owing to the challenge of the patient's immune system and the risk of transmitting the virus to the hospital staff.