In order to observe the influences of ATP on the bone marrow leukopoiesis, clinical tissue culture of bone marrow from normal rabbits, normal persons and patients with hypoplastic anemia was conducted. ATP solutions at various concentrations were added directly to the culture media and observations were carried out to see effect of ATP on the functions of neutrophils of bone marrow. As a result, it has been demonstrated that by adding an optimal amount of ATP the ontgrowth, cell density and wandering velosity of neutrophils were increased.