Research is required to determine the optimal approach for prophylactic platelet transfusions in patients with haematological malignant disorders. It has been suggested that thresholds for prophylactic platelet transfusions of platelet counts below 10 x 109/l should be investigated, as these may be equivalent in clinical effectiveness and associated with lower costs and fewer complications. An important concern in such investigation is the accurate estimation of platelet counts below 10 x 109/l. This study aimed to further examine the potential reduction in platelet usage that could be made if a lowered platelet transfusion threshold of 5 x 109/l was used in conjunction with an immunoplatelet counting method. Clinical and laboratory data from 130 haematology patients were used. Standard platelet counting was performed using Bayer H3 and ABX Argos analysers. Immunoplatelet counting was performed by flow cytometry using anti-CD61. The potential for reducing platelet transfusions included consideration of clinical criteria that influence prophylactic platelet transfusion use. The results indicated that the use of an immunoplatelet count with a 5 x 109/l platelet transfusion threshold would potentially reduce the number of transfusions by 10.4% in comparison with a 10 x 109/l threshold and standard automated platelet counting with the ABX Argos analyser, and increase the number of transfusions by 5.4% in comparison with the same threshold using the Bayer H3 analyser. The immunoplatelet count may aid the clinical decision to transfuse platelets, but would not necessarily lead to a reduced use of platelet transfusions.