Morphological and cytochemical characteristics of neutrophil in asian arowana, Scleropages formosus were examined by light microscopy and the composition of neutrophil granule were inferred in this study. The neutrophils were round or oval (12.0～17.0μm in diameter) and the nucleus round to three lobule-shaped. Three types of granules； acidophilic (eosinophilic) granule (αG), chromophobic granule (βG) and basophilic granule (γG) were observed in neutriphil. The αG was rod to spindle in shape (1.0×0.3μm) and observed in May-Grünwald (MG) preparation using distilled water and low molar (5mM) buffer. The acidophilicity of αG disappeared by Giemsa stain after MG. The βG was round to oval (<0.5μm in diameter) and peroxidase positive. The γG was round to oval (<0.3μm in diameter) and observed in MG preparation using alkaline (pH8.0) buffer and in Giemsa preparation. The γG was naphthol AS-D chloroacetate esterase positive. Yasumoto body (Y-body) was also observed in neutrophil. The Y-body was toluidine blue positive.