Morphological and cytochemical characteristics of leukocytes from redlip mullet (Chelon haematocheilus) were examined by light microscopy. Lymphocyte, monocyte and neutrophil were observed in the peripheral blood. Lymphocyte had round to oval nucleus with coarse chromatin-mesh. Cytoplasm was agranular or contained some basophilic (blue) granules (Lymphocyte Basophilic Granule, LBG). Monocyte had round to kidney-shaped nucleus with fine chromatin-mesh. Two types of granules, monocyte major granule (MMG) and monocyte minor granule (MmG) were observed in the monocyte. The MmG were classfy into two categories, small MmG (MmSG) and large MmG (MmLG), according to the size and staining characteristics. Neutrophil were round to oval and the nucleus round to lobule-shaped. Only one type of granule, chromophobic granule (βG) was observed in the neutrophils. The βG was round to oval, unstained by Romanowsky type stain and peroxidase positive. The Yasumoto body was also found in the neutrophil and toluidine blue positive (orthochromatically).