Severe haemophilia A and B (SHA, SHB) are inherited bleeding disorders affecting male patients and are characterised by low levels of circulating clotting factors VIII and IX respectively. Clinically low levels present with multiple recurrent bleeds into joints and muscle from the first couple of years of life. In addition patients may present with spontaneous and potentially fatal bleeding into any organ. The mainstay of treatment is replacement with the missing factor in the form of intravenous injections of factor VIII and IX. Clotting factors can be given to treat a bleed or can be given to prevent a bleed, and the latter is termed prophylaxis. Regular prophylaxis is the current standard of care and aims to decrease spontaneous bleeding events and resulting joint damage, and this requires patients to self-infuse factor into their veins two to four times week. Patient's compliance with prescribed regimen and recommendations has a significant influence on outcomes.