Zebrafish produce nearly identical hematopoeitic cell lineages to those found in mammals and other higher vertebrates. As in mammals, blood cell development proceeds in distinct waves, constituting embryonic (primitive) and adult (definitive) hematopoiesis. The conservation of genes such as scl, pu.1, c/ebpalpha, mpo, l-plastin, and lysozyme C in myelopoiesis and the corresponding expression patterns in zebrafish suggests that shared genetic pathways regulate this complex developmental process. In the zebrafish model system, experimental approaches have been applied, including RNA in situ hybridization, morpholino injections, and the analysis of mutant and transgenic fish lines, leading to improved understanding of the regulation in vivo of key molecular pathways with conserved roles in vertebrate myelopoiesis.