FVIII:C levels collected from patients with mild haemophilia A displayed a significant median increase of 6.5% with proceeding age (p = 0.0013). Patients with moderate haemophilia A (and carriers of haemophilia A) showed a non significant median increase of 1.05% (carriers 8%). Eight patients showed FVIII:C levels at last blood withdrawal that indicated a change of severity from moderate to mild haemophilia A. A significant correlation was found between FVIII:C and VWF:RCo (p = 0.0203) and AFP (p < 0.0005). The correlation between FVIII:C and triglycerides and LDH was significant negative (p < 0.0005). No significant correlation could be found for FVIII:C and co-morbidity, fibrinogen, cholesterol and VWF:Ag.