Granulocyte transfusions have been used since the 1960s with varying degrees of clinical success in the treatment of infection in patients with neutropenia or inherited granulocyte disorders. A number of studies have indicated that efficacy may well be associated with the dose of granulocytes delivered. Collection of granulocytes using modern apheresis machines and corticosteroid administration yields approximately 20 to approximately 30 x 10(9) neutrophils, unlikely to be adequate for treating an established infection. The administration of G-CSF to healthy donors has resulted in average granulocyte yields up to 8 x 10(10) cells. Normal or near normal blood neutrophil counts are often attained when these concentrates are transfused to neutropenic recipients, and these levels are sustained for up to 24 h. G-CSF-primed granulocytes appear to be functionally normal by both in vitro and in vivo measurements. Adverse effects experienced by recipients are similar to those seen with traditional doses of granulocytes. G-CSF administration to donors is well tolerated. Controlled clinical trials are needed to determine the therapeutic efficacy of G-CSF-primed granulocyte transfusions.