A mild haemophilia A (factor VIII [FVIII] 10%) was discovered in a 73-year-old man during the preoperative haemostasis tests before a total knee arthroplasty for treatment of degenerative senile arthropathy. No history of previous abnormal bleeding was noted in spite of several previous challenging surgical procedures. Acquired haemophilia was ruled out and no other cases of haemophilia were found in the family. The surgery was successfully performed under recombinant FVIII aimed at achieving an FVIII level above 60%. This therapy induced the transient appearance of low-titre FVIII antibodies. A still unpublished mutation within the exon 3 (Gly73Ala) was found with molecular studies. This case report underlines the importance of haemostasis tests before high-risk bleeding surgical procedures even in elderly patients without a past history of haemorrhagic tendency.