Light and transmission electron microscopy of Batillus cornutus hemocytes revealed differences that the morphological distinctions between blast-like cell, granulocytes and hyalinocytes. Base on the morphological characteristics of the cells, we identified the eight types of hemocytes and present a categorization of the hyalinocytes into six sub-categories. The hemocytes of B. cornutus were observed basophilic cell under the light microscopy. Blast-like cells had a spherical profile with a central nucleus filling almost the whole cell. Granulocytes were characterized by presenting variable numbers of granules. This cell had spherical shape with diameter 7 ¥ìm and smooth endoplasmic reticula, granules, mitochondria, glycogen granules in the cytoplasm. Hyalinocytes were the most abundant cell type. Especially, hyalinocyte VI had iirregular an amoebal shape and observed autophagosome and heterophagosome in the cytoplasm. From these results, it is concluded that there are eight types of cells in the hemolymph of B. cornutus. Further studies are now needed to identify the role of these hemocytes in the enzymological and immunological response.