Bacterial and fungal infections progress more rapidly during neutropenia. Some of them, despite optimal antimicrobial therapy, fail to respond. In other cases, no effective antimicrobial agents may be available. Granulocyte transfusions (GT) have been used in these situations for decades (1). Current practice using mobilization with granulocyte – colony-stimulating factor (G-CSF) and dexamethasone together with optimal pheresis techniques allows the collection of 8 10 10 neutrophils with apparently normal function from healthy donors after only 12 h (2). Recent series, including the report by Kim et al. (3) published in the current issue of Cytotherapy , have reported infusions of 2 – 8 10 10 neutrophils/transfusion, with median increments in the absolute neutrophil count (ANC) of 1 – 2000 10 9 /L at 24 h (3 – 5). Multiple single-center reports have documented this strategy as safe and feasible. So why is it not a mainstream practice? The concern with GT-induced acute lung injury, described 30 years ago and less frequently seen today (6), still lingers, but the question seems to be more concerned with effi cacy. Response rates are diffi cult to measure and have varied between studies, and some randomized controlled trials (even if plagued by methodologic issues) have shown no benefi t (7). Still, a 2005 Cochrane review, analyzing the results of eight trials conducted between 1977 and 1984, estimated a mild overall benefi t (8), and most reports over the last few years have indicated acceptable responses in infections that were refractory to conventional therapy (9,10). Kim et al. (3) used GT to treat 138 episodes of infection in 128 patients at the Seoul University Hospital (Seoul, Korea), and report control of the infection in about half of the cases. This seems to be in the same range as experiences at the National Institutes of Health (NIH, Bethesda, MD, USA) in patients with aplastic anemia, reported by Quillen et al. (5) in 2009. Some experts anticipate that the ongoing randomized controlled trial RING (Safety and Effectiveness of Granulocyte Transfusions in Resolving Infection in People with Neutropenia; ClinicalTrials.gov, identifi er NCT00627393), supposed to fi nish enrolling patients in 2012, will answer the effi cacy question, but until then we have enough data to make the following statements.