Purpose The objective of this study was to evaluate the long-term outcome and prosthetic survival of primary total knee arthroplasty in haemophilic patients. It was hypothesized that the infection and revision rate are higher and the outcome inferior when compared with patients without haemophilia. Methods Between 1985 and 2004, forty-three consecutive primary total knee replacements were performed in thirty haemophilic patients. These patients' charts were reviewed retrospectively. Twenty-five patients (34 knees) were available for clinical and radiological follow-up. The outcome was assessed using the Knee Society score, WOMAC and Kaplan-Meier survivorship analysis. Results An haematogenous infection occurred in two patients. In three patients, component revision was needed: two because of an infection and one because of a mechanical failure. After a mean follow-up of 9.6 years (2-20), 94% of the patients rated their result as either excellent or good. At time of follow-up, the Knee Society Score averaged 73.3 points (range, 29-100) and showed a significant gain (p \ 0.001) compared to preoperative. Flexion contracture could be reduced significantly (p \ 0.001) from 18.1°preoperatively to 8.4°at follow-up, whereas flexion remained unchanged. When infection or any component replacement was set as endpoints, the 10 years prosthetic survival was 90 and 86%, respectively. Conclusion Total knee arthroplasty in haemophilic patients is a reliable treatment that results in pain relief and functional improvement with a low risk of postoperative infection. However, neither the postoperative infection rate nor the functional result does reach the same level as in a population not affected by haemophilia. Level of evidence IV.