Abstract
The bone marrow is one of the most stable and resilient organs in the body, but it can be critically damaged by environmental stresses and insults (unknown and known) and by various chemotherapeutic agents. Either a dangerous depression or an excess of blood cell elements can result. Aplastic anemia and the leukemias are the extremes of these pathologic reactions. The author stresses the prevention of iatrogenic damage of the bone marrow and reviews the available therapy for aplastic and hyperplastic blood dyscrasias.