We have observed that it is a common practice in the United Kingdom to follow transfusions of packed red blood cells in neonates with an injection of frusemide. The purpose of this paper is not to comment on whether or when transfusions should be given, but on the use of frusemide with blood transfusions. On reviewing manuals of neonatal intensive care we were only able to find one that recommended giving frusemide with blood transfusions [10]. When we asked clinicians for their rationale for this practice, a consistent answer was that it would diminish the vascular overload provoked by the transfusion. Is this reasonable? The origins of this practice appear to be reports describing the haemodynamic eects of blood transfusion in chronic anaemia. Duke et al. [4] pointed out that in anaemic but euvolaemic patients transfusion may produce hypervolaemia. Gupta et al. [6] measured pulmonary capillary wedge pressure as an index of left ventricular filling pressure before and after the transfusion of one unit of blood, at a rate of 300 ml/h, in adults with chronic severe anaemia. Patients who recevied frusemide at the start of the transfusion showed a reduction in wedge pressure, in contrast to those who did not, in whom there was a rise in wedge pressure. DePalma and Luban [3] have recommended that patients in heart failure should be given no more than 2 ml/kg per hour of red blood cells. However, most preterm newborn babies receiving ‘‘top up’’ red cell transfusions are not in heart failure. In addition, Duke et al. [4] published their report at a time when only whole blood was used for transfusion. Present day practice, based on specific component therapy, is for ‘‘top up’’ transfusions to consist of red cell concentrates with an haematocrit of around 50%‐70%.