The authors report on two non-Hodgkin's lymphoma cases which showed markedly enhanced Ga-67 uptake of granulopoietic area induced by recombinant human granulocyte colony-stimulating factor (rhG-CSF) administration. The rhG-CSF is a newly developed agent for reduction of infections, which stimulates the proliferation and differentiation of granulopoiesis. Use of rhG-CSF is becoming increasingly frequent because the indications are so broad that most patients with intensive chemotherapy for malignancies benefit from undergoing this treatment. In this study, the results of the two cases were: 1) G-CSF enhanced the accumulation of Ga-67 citrate in the granulopoietic area; 2) the marked uptake of red marrow looked like involvement; and 3) in contrast, the involved area became relatively "cold." These findings should be considered in the interpretation of Ga-67 scintigraphy.