The VAT-1 protein is present in the electric organ of marine rays where it is suggested to play a central role in nerve signal transmission. VAT-1 homolog protein was also identified in mouse and human but its function remains to be determined. We have investigated VAT-1 homolog in zebrafish Danio rerio since it is an excellent model amenable to the combination of genetic, molecular and embryological studies. Amino acid sequence analysis shows that the zebrafish VAT-1 homolog shares approximately 51-61% identity with the electric ray, mouse, and human counterparts. By in situ hybridization, vat-1 homolog mRNA is first observed in the trigeminal nuclei at the 8-somite stage. At 20-somite stage, vat-1 homolog is detected in the brain, namely in primary clusters of neurons, in the epiphysis and in the hindbrain. vat-1 homolog is also present in the neural tube but this expression disappears after 72 h post-fertilization. At 24 h post-fertilization, vat-1 homolog starts to be expressed in the developing gut. At later stages, vat-1 homolog is present throughout the brain, appears in the maturing retina and the pharyngeal cavity.