Constitutional symptoms and pancytopenia are occasionally the initial presentation of pediatric brucellosis. Therefore, in endemic areas, in children with pancytopenia, both brucellosis and malignancy should be included in the deferential diagnosis. We report here a child with pancytopenia and hepatosplenomegaly as manifestations of brucellosis in whom bone marrow morphology and flow cytometry data revealed hemophagocytosis, left shift in myeloid cells and activation changes in antigenic properties of T and B lymphocytes and monocytes. The patient had an uneventful and complete recovery after appropriate antibiotic therapy. Our report demonstrates that bone marrow and flow cytometry findings in children with brucellosis may include significant reactive changes in hematopoiesis.