Febrile non-hemolytic transfusion reaction (FNHTR) is the most common adverse effect of blood transfusion. FNHTR is usually immune mediated due to the reaction of white cells antibodies in the recipient's plasma with the leukocytes contanied in the transfused blood components. In some patients, especially recipients transfused with platelets, cytokines are implicated in this reaction. The differential diagnosis may be difficult, especially when co-morbid disorders such as infection or malignancy, and certain treatments, may cause a similar spectrum of symptoms. In differential diagnosis, acute haemolytic transfusion reaction, bacterialy contaminated blood products and transfusion associated lung injury must be exlcuded. Repeated severe FNHTRs necessitate leucocyte depletion of blood components.