In this prospective two-center before-and-after study, premature neonates received platelet transfusions according to two different guidelines. In the first, decision to transfuse was based on platelet counts. In the second, decision to transfuse was rather based on platelet mass (platelet count X mean platelet volume). The proportion of neonates who received at least one platelet transfusion was 3.6% during the first period while it was 1.9% during the second (p < 0.002). The incidence of bleeding, including intraventricular hemorrhage, was lower during the second period. The authors conclude that platelet mass-based guidelines may be useful and safe. The study was well conducted and the authors recognized its most important limitations (imbalance between the two groups, better compliance to guidelines caused by the study, etc.). However, the Hawthorne effect is not really addressed, and it must be recognized that the improvements observed in the study might be attributable to the change in guidelines, rather than to the new guidelines themselves. Nevertheless, this study is original, its results are important, and the question (platelet mass-based transfusion guidelines) merits further studies. – Jacques Lacroix