Viruses consistently present a major health danger and require a proper, balanced reaction from our immune system. Among viruses, human influenza viruses often cause morbidity and mortality, especially in populations at high risk. These viruses cause apoptosis in peripheral blood monocytes and tissue culture cells. Hemophagocytosis-induced pancytopenia has also been frequently correlated with the newly emerging influenza virus infection in latest years. Leukopenia, particularly in influenza B virus, has been discovered to be a common finding in influenza infection. If the virus and the resulting antiviral reaction continue, the inflammatory feedback on the hematopoietic system becomes chronic. Here, we have reviewed effect of Influenza on hematological factors specially cytopenia.