The immuno-haematological safety of blood remains an important and recurring issue in blood transfusion practice. Data concerning morbidity and mortality from blood transfusion is sparse in Nigeria however and while the current efforts at reduction in the incidence of adverse consequence of blood transfusion is encapsulated in the concept of Haemovigilance, the Nigerian blood transfusion service is yet to institute the practice. A prospective study of 462 transfusions at the Obafemi Awolowo University Teaching Hospital was done to evaluate the incidence and pattern of transfusion reactions in the hospital. The overall incidence of transfusion reactions is 8.7% (40 cases), with febrile nonhaemolytic transfusion reactions (FNHTR) constituting 65% of these. The incidence of adverse reaction is significantly related to a positive history of previous transfusion (p = 0.0039). Efforts must be sustained at evolving a system to minimize the incidence and consequences. The development of a haemovigilance system in which data regarding all transfusions carried out in Nigerian hospitals is collated and analyzed is necessary. The advent of the National Blood Transfusion Service (N.B.T.S) in Nigeria with Zonal centres in the six geopolitical zones of the country offers an opportunity for setting up a national haemovigilance programme.