Haemovigilance is a national system of surveillance and alarm, from blood collection to the follow–up of the recipients, gathering and analysing all untoward effects of blood transfusion in order to correct their cause and prevent recurrence. In France haemovigilance was created by law and notification of transfusion incidents is a legal obligation. The haemovigilance network associates local correspondents in each hospital and blood centre with regional co–ordinators and is centralised by the Agence Française du Sang. After 4 years the incident reporting rate is 2.3 per 1000 allogeneic blood components transfused, justifying for example increased efforts in the prevention of bacteria–associated transfusion reactions, haemolytic transfusion reactions or vascular overload. However, haemovigilance still has to be strenghtened by improved information management or further progress in standardisation from one region to the other. The most important factor of success is collaboration between blood centres and hospitals. Haemovigilance clearly is the ultimate quality indicator of a transfusion service.