Febrile non-hemolytic transfusion reactions (FNHTR) are the most frequently reported acute adverse effects of blood products, and should be notified within 48 h according to the hemovigilance regulation. In order to study the conformity of these notifications and to search for factors associated with non-conformity, we retrospectively studied all FNHTR notified by voluntary centers of the AIRSEH group from 1st September 1994 to 31st December 1999. Seven hundred and sixty-one FNHTR were registered by 10 centers, most of them were benign (grade 1); 67.8% were non-conform. The non-conformity was associated with the number of biological investigations performed (median number, respectively, 4.24 and 2.94--P = 0.038--in non-conform and conform notifications--P = 0.038) in univariate analysis. Using a logistic regression model, center and severity were the only two factors significantly associated with non-conformity. Different center practices, and in particular the interface between the hospital and the blood bank, may be responsible for the effect center. Moreover, the non-conformity concerns first of all benign FNHTR. A stronger separation between alert and epidemiological surveillance is proposed in order to improve the notifications' conformity.