The first aim of this study was to confirm the presence of hypotension blood transfusion reactions and to assess the part of hypotension as a principal event, as defined by the literature but not characterized in French haemovigilance data. As well, recent series of several cases led us to consider a possible incidence increase.Using a retrospective observation, the haemovigilance data from 2000 to the end of 2007 of two French regions were reviewed. During this period, 1159657 blood units were transfused by nearly 100 hospitals and 3727 adverse reactions observed.One hundred and sixty-eight adverse reactions with hypotension were noticed and analyzed, representing 4.5% of all transfusion reactions and revealing an incidence of 14.5 for 100000 blood units transfused. It turned out to be mostly male recipients, severe reactions and appearing rather in the beginning of transfusions. Although platelets having greater incidence, all types of blood products may be involved. The clinical diagnosis was the following: 40 to 47% were classified as febrile reactions, 13 to 17% were allergic reactions, 8 to 9% were due to immunologic and/or haemolytic reactions, 5 to 7% resulted of cardiologic disorders, 5% resulted of hypovolemic contexts and 22% were unexplained hypotensive transfusion reactions.In about three cases out of four, transfusion-induced hypotension was associated with other clinical reactions. Indeed, hypotensive transfusion reactions were identified, having an incidence of 3.2 for 100000 blood units transfused. Furthermore, there was no explanation found for the incidence increase in our region during 2007. A national study was suggested to analyse the national data as well as a prospective study to clear out this type of transfusion reactions.