The generation of drug resistant bone marrow may facilitate the develo
pment of aggressive chemotherapeutic regimens that might otherwise be
lethal due to marrow toxicity. With the availability of technology tha
t permits in vitro manipulation of human marrow and peripheral blood s
tem cells, it is now possible to introduce genes that confer drug resi
stance to these hematopoietic progenitors. Animal models and in vitro
work with human progenitors using drug resistance genes are reviewed.