Venous thrombosis is a very rare occurrence in patients with haemophilia A. The majority of these cases occurred during or after the administration of clotting factor concentrates. We report the case of a patient with severe haemophilia A, who spontaneously developed a deep venous thrombosis (DVT). The thrombosis occurred in the superficial femoral vein with an extension in the profunda femoris vein. Neither any local anatomic compression nor any predisposing thrombophilic risk factors were identified. Treatment with recombinant factor VIII at prophylactic doses associated with unfractionated heparin led to a successful resolution. This case illustrates the possibility for severe haemophilia patients to develop authentic spontaneous DVT without anti-haemophilic treatment and predisposing risk factors.