Recent studies have shown that the rhombomeric bulges of the developing vertebrate hindbrain reflect segmental mechanisms that generate pattern in this region of the CNS. Although little is known of the genetic basis of this segmentation, in situ hybridization studies have provided circumstantial evidence that certain 'zinc-finger' and homeobox genes have roles in the development of segments in the early mouse hindbrain. We discuss the implications of these findings for the function of these genes in hindbrain development.