Neutrophil granules (NG) of adult (mature) far eastern brook lamprey Lethenteron reissneri [L. sp. S (souther form)] were classified into two types of stratified [two-layer; inner layer (L0) and outer layer (L1)] granules (type 1, NG1a; type 2, NG2), like as larva (ammocoetes) of this species. The L0 of NG1a and L0 of NG2 in adult neutrophils were chromophobic, and L1 of NG1a and L0 of NG2 showed chromatophilic. The stainability of those chromatophilic layers with May-Grünwald (MG), Giemsa, or MG-Giemsa were varied [chromophobic, eosinophilic or basophilic (orthomethylenophilic or metaazurophilic)] with a slight difference to larva. As seen in larval neutrophils, these layers were positive for alkaline phosphatase,α-naphtyl acetate esterase and Sudan black B, and some enzymes (acid phosphatase, ꞵ-glucuronidase, and naphthol AS-D chloroacetate esterase) were detected in the L0 of NG2. Alpha-naphtyl acetate esterase was positive in L0 of NG2 of adult neutrophils. Both larval and adult neutrophils lacked peroxidase.