Abstract: The surface ultrastructure of the gill in channel catfish Ictalurus punctatus was investigated by using scanning electron microscopy. The result showed that the surface architecture and ultrastructure of I.punctatus' gill and secondary gill lamellae were similar to those of other teleosts. The surface of gill arches and gill rakers was covered with pavement cellswhich were characterized bycircular microridges, and secreting-holes were found among cells on the surface of gill arches. The base part of gill rakers were bigger in terms of diameter. The pavement cells' surface of gill filaments' middle part was characterized by microridges with fine lateral protuberances on both sides which were either fused or interruped, while the microridges disappeared on the pavement cells' surface on both top and base parts of gill filaments, forming dense granulated protuberances. The height and interlamellar space of secondary gill lamellae in I.punctatus were relatively higher and bigger, respectively. Finally, the relationship between the gill structure of this species and its physiological function was discussed.