Although guidelines exist to deal with some aspects of platelet transfusion practice, many important clinical issues have not been addressed in large randomized controlled trials (RCTs). Slichter et al. conducted a RCT of prophylactic platelet transfusions to determine the effects of the dose of platelets on clinical signs of bleeding, the use of platelet and red cell transfusions, changes in the recipient's post-transfusion platelet count, days to next transfusion and adverse events (Effects of Prophylactic Platelet Dose on Transfusion Outcomes [PLADO] trial). The primary end point of the study (i.e., the percentage of patients in each group with at least one episode of bleeding of grade 2 or higher according to the WHO criteria) was not significantly different (71, 69 and 70% of patients in the low-, medium- and high-dose group, respectively). According to these data, one can conclude that the dose of platelets transfused has no significant effect on the incidence of bleeding in patients with hypoproliferative thrombocytopenia and platelet counts no greater than 10 × 10⁹/l.