Morphological and cytochemical characteristics of neutrophil in red sea-bream, Pagrus major were examined by light microscopy. The neutrophils were round to oval (7.5-11.5μm in diameter) and the nucleus round to kidney-shaped. Granules of the neutrophil were classified into two types； acidophilic granule (αG) and chromophobic granule (βG). The αG was round to oval (0.4 μm in diameter) and stained with May-Grünwald (MG) and MG-Giemsa (MGG) stain. The Giemsa staining pattern of the granule was influenced by pH and concentration of diluent of the staining solution. Some enzymes, such as acid phosphatase, α-naphtyl acetate esterase and naphthol AS-D chloroacetate esterase were detected in the αG. The βG was round to oval (≦0.5μm in diameter) and unstained by Romanowsky type stain (MG, Giemsa and MGG). This granule was peroxidase and sudan black B positive. The Yasumoto body (Y-body) was also found in the neutrophil and toluidine blue positive.