Staufen, a double stranded RNA binding protein, has been shown to be involved in creating and maintaining cellular asymmetry in the Drosophila oocyte, neuroblast, and mammalian neuron. Staufen binds to the 3' UTR of specific mRNAs and acts in their localization and anchoring to various subcellular domains. Staufen's molecular interactions during development have been limited to investigations in Drosophila melanogaster. Since a vertebrate Staufen has not been studied in a developmental system, the aim of this study was to clone and characterize a staufen orthologue gene in the vertebrate developmental model, zebrafish. The zebrafish staufen-like sequence shows a 64% homology to the human staufen with a 81.2% homology in the highly conserved double stranded RNA binding domain (dsRBDs). Staufen maps on the LN54 radiation hybrid panel to linkage group 6, 16.25 cR from Z265 between fb22h06 and fi16e01. Northern blot and in situ hybridization showed that staufen is expressed both maternally and zygotically. Zygotically expressed staufen is localized to the developing nervous system and at 24 h is highly concentrated in the subventricular zone of the developing brain. Maternally expressed staufen is dispersed in the mature oocyte and early embryo. In the adult, staufen is expressed in specific brain nuclei, the testis, neurons and Leydig cells.