In this paper the case of a man with haemophilia A is presented. At the age of 18 years an acute lymphatic leukaemia was observed. The case report demonstrates that even in the presence of a severe plasmatic coagulopathy an acute lymphatic leukaemia can be successfully treated with intensive chemotherapy, if the monitoring of the coagulation values and the substitution of antihaemophilic globulin and thrombocytes are guaranteed. Only 4 cases of haemophilia and acute leukaemia in the same patient are described in the literature. So we believe that the association of these two rare disorders is merely accidental.