Background: Acquired haemophilia A (AHA) is a rare bleeding disorder caused by an imbalance in the immune system leading to the production of factor VIII antibodies. In half of the cases, the underlying cause is not known. Clinical History: We report on a patient with AHA and Kaposi’s sarcoma (KS), which is caused by the human herpes virus 8 (HHV-8). The patient presented with appendicitis and developed several severe post-operative haemorrhages. He spent 3 months in intensive care due to long and difficult infections. While recuperating on the ward, the patient developed KS in the lower extremities. He had a positive HHV-8 infection. Discussion/Conclusion: Due to its latency and replication in the lymphoid system, HHV-8 is an ideal candidate for causing an imbalance in the immune system in susceptible patients. Our conclusion is that AHA was caused or prompted by the HHV-8 infection. Since HHV-8 viral infection is often subclinical, viral testing might be an important tool in acquired haemophilia diagnostics even when viral symptoms are absent.