OBJECTIVE The objective of this study was to determine the effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) administration in septic patients with neutropenia. METHODS Twenty consecutive septic patients were administered rhG-CSF subcutaneously (2 microg x kg(-1) x d(-1)) for 5 days (group G). They were compared with 14 septic patients treated earlier without rhG-CSF (group N). All patients in both groups met the criteria of total leukocyte count (TLC) less than 5,000/mm3 and C-reactive protein (CRP) more than 10 mg/dL. Changes in TLC, absolute neutrophil count (ANC), CRP, respiratory index (RI), Acute Physiology and Chronic Health Evaluation (APACHE) II score, and Goris's Multiple Organ Failure (MOF) index were evaluated. In addition, nucleated cell count (NCC), differentiation in bone marrow aspiration, neutrophil phagocytic and bactericidal activity, serum concentrations of interleukin-6 (IL-6) and IL-8 as inflammatory markers, and plasma concentration of leukocyte elastase (LE) as an indicator of the tissue injury were evaluated in group G. RESULTS In group G, TLC, ANC, NCC, and neutrophil functions increased significantly, whereas CRP, IL-6, and IL-8 decreased reciprocally. There was no deterioration of LE and RI. Consequently, the APACHE II score and MOF index improved. In group N, however, CRP showed no change concomitant with the APACHE II score and MOF index. CONCLUSIONS Administration of rhG-CSF attenuates inflammatory responses without inducing tissue injury in septic patients with neutropenia.