The bone marrow failure syndromes consist of a number of rare diseases, in which there is ineffective hematopoiesis by the bone marrow. Subsequently, absent or decreased production of a single cell line, single cytopenia, or of all cell lines, and pancytopenia, develops. The mechanisms of hematopoiesis and the defects that result in bone marrow failure are beginning to be better understood. This paper will review the genetic and molecular basis of several important bone marrow failure syndromes in children, Fanconi anemia, Shwachman-Diamond syndrome, Diamond-Blackfan anemia, congenital amegakaryocytic thrombocytopenia, dyskeratosis congenita, and severe congenital neutropenia, and the recent discoveries that have enhanced our understanding of the pathogenesis of these diseases. (c) 2005 Elsevier Inc. All rights reserved.