Morphological characteristics of hemocytes from leaf shrimp Nebalia japonensis and pea crab Pinnotheres sinensis were examined by light microscopy. Only a single type of hemocyte, granulocyte, were observed in the hemolymph of the leaf shrimp. The hemocyte was spindle to oval in shape and characterized by the presence of numerous small granules. The granules were round (≦0.3 μm in diameter) and classified into two types, eosinophilic granule and basophilic granule. On the other hand, two types of hemocytes, eosinophilic small granulocytes and eosinophilic large granulocytes, were observed in the hemolymph of the pea crab. The former had small-sized (round to oval, ≦0.5 μm) eosinophilic granules, and the latter had large-sized (round to oval, ≦1.5 μm) eosinophilic granules. Based on the present results and those of other crustaceans previously reported, we make a speculation about the evolutional process of crustacean hemocytes.