The cytochemistry and staining of granula in peripheral blood granulocytes in healthy carp (Cyprinus carpioL.) are described. Blood smears were stained for periodic acid‐Schiff (PAS), peroxidase, oxidase, alkaline and acid phosphatase, α‐naphthyl‐acetate esterase, α‐naphthyl‐butyrate esterase, naphthol‐AS‐chloroacetate esterase (AS‐D), naphthol‐AS‐acetate esterase and β‐glucuronidase. Different granula types were shown by triazid‐staining (eosinophil and neutrophil granula) and methylenblue‐staining for basophil granulation. Toluidinblue‐staining was used for basophil granulocytes. Lipids were shown by the Sudan‐black‐reaction. Four granulocyte subpopulations are described: neutrophil, heterophil, basophil and eosinophil granulocytes. Neutrophils possess all tested granula types, whereas heterophil and basophil granulocytes show only basophil granula. Neutrophils and heterophils show no activity of the tested esterases with the exception of AS‐D. Only neutrophils were peroxidase‐positive. Alkaline phosphatase and β‐glucuronidase were not detected in granulocytes. Basophils and especially eosinoph