Abstract: The present paper deals with the development of Eimeria kwangtungensis Chen et Hsieh, 1960 inside its host Ophiocephalus argus. Taking place in the same host this eimerian species has three developmental stages, schizogony, viz. gametogony and sporogony. Both schizogony and gametogony occur at the place above the nucleus of the epithelia cells of pyloric caeca and anterior intestine. Mature schizonts are spheric or elliptic, with 8—14 merozoites in the shape of banana. Eosinophilic granules were not found throughout the developmental course of macrogamete. Basophilic granules vary before and after the formation of oocyst wall. Mature microgametocyte has many microgametes of crescent shape. Sporogony takes place in pyloric caeca and whole intestine.