Platelet transfusions are established as effective treatment for thrombocytopenic bleeding. However, the indications for prophylactic platelet transfusions are being reconsidered because of the greatly increased demand for platelet concentrates. Platelet refractoriness is the main clinical problem associated with repeated platelet transfusions. This is most frequently due to HLA alloimmunisation or non-immune platelet consumption associated with clinical factors such as septicaemia. The initial management of refractory alloimmunised patients is to use HLA-matched platelet transfusions. If there is no improvement with HLA-matched platelet transfusions, platelet crossmatching may identify the cause of the problem and help with the selection of compatible donors. Other measures used to improve responses to platelet transfusions are usually ineffective. There has been considerable interest in methods to prevent HLA alloimmunisation and platelet refractoriness and particularly in leucocyte depletion of blood components. The use of leucocyte-depleted blood components has other benefits for multitransfused patients, but further studies are needed before the routine use of leucocyte-depleted blood components can be recommended for patients likely to receive repeated platelet transfusions.