Prophylaxis of bleeding in severe haemophilia is defined as the regular administration of missing factor concentrates to prevent haemarthroses as well as other bleeding episodes. This management is the gold standard of treatment in children with severe haemophilia, however the optimal time of prophylaxis initiation as well as the intensity of therapy in young children remain a matter of controversy. There are several models of prophylaxis, e.g., Swedish (Malmoe), Canadian, French (COMETH recommendations) or proposed by Kumik et al. in 2009. The development of inhibitor is the most serious iatrogenic complication affecting children with haemophilia. Several data suggest that prophylaxis initiated at the early age may increase the risk of inhibitor formation, however recent studies (CANAL or made by Chambers et al.) showed that early exposure to factor VIII was not directly associated with higher incidence of inhibitor as compared to children treated later during the first year of life. On the other hand early prophylaxis (initiated between 6th and 12th month of life) can minimize the intensity of the exposure to FVIII and prevent the inhibitor development resulting in improvement of child's quality of life. Undisputable is that prophylaxis of haemophilia is associated with a lower risk of inhibitor development than on-demand therapy.