The present study focused on the morphological characterization of hemocytes of Sepiaofficinalis and the histological structure of its hemopoietic organ (white body). Haemolymph was collected from the branchial heart with syringe then blood smears were prepared and stained with Haematoxylin& Eosin (H&E).White body was dissected and fixed in Kahl?s fixative for histological studies also other pieces were fixed in glutardehyde for the preparation of semithin and ultrathin sections. Three main types of hemocytes were identified by light microscope: Hyalinoytes, granulocytes and agranulocytes.The histological structure of hemopoietic organ (white body) of cephalopods revealed that it is a multilobed organ enclosed by a thin fibrous connective tissue capsule that consists of collagenous fibers. Hemocytes within the white body were enclosed in a supportive connective tissue fibers that form a network of small unites in which hemocytes are grouped in clusters.