Abstract: The peripheral blood cells of the mandarin fish,Siniperca chuatsi (Basilewsky) are morphologically described. On the stained smears five major cell types were recognized: erythrocyte,thrombocyte,lymphocyte,monocyte and neutrophil. Among these cells,thrombocyte is the smallest while neutrophil the biggest; and monocyte is the least encountered leucocyte,while thrombocyte the most abundant Mitochondria and Golgi complex were found in erythrocyte and structure similar to myeloid body in mitochondria of lymphocyte. The granulocytes were further classified into two types: type Ⅰ and type Ⅱ granulocytes based on the structures of intratytoplasmic granules and other organelles. The type Ⅱ granulocyte is similar to the neutrophil of other fish,but further stUdies are required to determine the type Ⅰgranulocyte. The observations of immature and dividing erythrocytes in the blood indicate that Peripheral erythrocytes may develop directly in the cireulation. In addition,developing macrophages and cells with chanaterishcs of plasma cells were found in the blood.