We have described the formation of the zebrafish central nervous system. The spinal cord has the simplest organization and was considered first, followed by the forebrain, midbrain and hindbrain. We have discussed many studies that have revealed the molecular mechanisms, including extrinsic signals and intrinsic responses to them, underlying the establishment of nervous system regions and the wide diversity of neuronal cell types of which they are comprised. Wherever possible, we have tried to compare what has been learned from zebrafish with what is known in other vertebrate species. The simplicity of the developing nervous system makes zebrafish embryos particularly amenable to studies of nervous system development. Thus, many aspects of nervous system patterning that were unknown from other vertebrates have been revealed by studies in zebrafish. However, the relationship between embryonic and adult nervous system morphology is still not entirely clear and remains an important avenue for further studies.