RESUMO
Diagnosis of diseases is mainly possible using previous available knowledge of healthy conditions such as normal physiological parameters and values. There is no information on the morphology of the various blood cells of the native ducks of the north of Iran. Therefore blood samples were collected from 100 apparently healthy adult green head Iranian ducks of both sexes. The smears were prepared and stained with Giemsa and new methylen blue technique. The stained smears were studied by light microscopy and the size of blood cells were determined by micrometry. Results of this study showed blood cell morphology in native ducks of north of Iran were similar to chicken and other birds. The size of red blood cells in these ducks were smaller than Indian ducks. Azurophilic granules were not seen in native duck's monocytes