A number of closely related avian related cause the leukosis / sarcoma (L/S)
group of transmissible benign and malignant neoplasms of chickens (Fadly and Payne, 2003)
The most common of these neoplastic diseases seen in field flocks is lymphoid leukosis. Diagnosis of
lymphoid leukosis depends on isolation and characterization of the etiologic virus, clinical signs
and pathobiology and epizootiology of the disease (Fadly and Payne, 2003).To the best of our knowledge
no study has been done to evaluate the cytology of bone marrow in cases of lymphoid leukosis