A human native immunoglobulin liquid preparation for intravenous injection, was used in combination with antibiotics and G-CSF to study its efficacy and safety in 49 patients with severe infections (Granulocyte counts were <or= 1000/ microliters, Body temperature was >or= 38 degrees C) which had not responded to antibiotic and G-CSF therapy of a 3-day or more duration. As a result of the Committee judgment, 49 patients were included in this study; 30 (61.7%) were included in efficacy and safety analysis. The analysis of 30 patients consisted of 9 patients (30.0%) with suspected septicemia, 5 (16.7%) with pneumonia, and 4 (13.3%) with septicemia. All patients had severe underlying diseases such as leukemia and malignant lymphoma. Clinical efficacy of Immunoglobulin preparation was judged by the doctors in charge to be "excellent" and "good" in 70.0% of the total cases. The rate of effectiveness was calculated from the results of the Committee judgment was 83.3% when "excellent" and "good" cases were included. No side effects were observed in all cases. Our results suggest that the immunoglobulin in combination with G-CSF is very effective on patients with severe infections.