The filtration of marrow directly into collection glasses eliminates additional filtration steps and therefore may potentially reduce the incidence of inadvertent microbial contamination.In this study, we describe a new filtering technique that uses a disposable blood transfusion device with a filtration membrane and compare it to the method previously described by Thomas.We studied the fat, bone chips, clots and activity of the hematopoietic progenitor cells, total mononuclear cells, CD34+ cells, and engraftment following filtration by each method.The two techniques were shown to be comparable in terms of these parameters.Furthermore, when compared with historical controls, this method may result in a reduced incidence of microbial contamination compared to filtration using successive stainless steel screens.This new system should be regarded as a cheaper alternative to the stainless steel screen method for BM filtration, which results in less contamination.