Platelet concentrates (PCs) are transfused mainly to patients with haematological disease. World-wide, the use of platelets is still increasing due, in part, to more intensive treatment schedules for such patients. Patients transplanted with cytokine mobilised peripheral blood stem cells (PBSC) have a shortened duration of thrombocytopenia and require fewer platelet transfusions. The principal thrombopoietic cytokine--megakaryocyte growth and differentiation factor (MGDF)--has been identified and is now being evaluated in clinical trials. MGDF treatment is likely to be widely used in patients with haematological malignancies to shorten thrombocytopenia resulting from marrow failure. Platelet transfusions will still be required in patients with malignant disease pre- and early post-treatment before MGDF is effective, and in patients with thrombocytopenia caused by massive blood loss or following major surgery. MGDF will, however, reduce the overall requirement for platelets. Transfusion of blood components is associated with a number of adverse effects including viral transmission. Novel strategies such as photodynamic treatment of blood components may maximise the safety of PCs. Erythropoietin (EPO) is clinically indicated for correction of anaemia in a minority of patients and will not significantly affect the requirement for red cell transfusions.