We studied the efficacy and safety of a combination therapy with sulbactam/cefoperazone (SBT/CPZ) and amikacin (AMK) on severe infections in the patients with hematological disorders. We administered SBT/CPZ and AMK to 65 patients and analyzed the result of 57 patients, except for 8 drop outs, for evaluation. The overall clinical efficacy of this combination therapy was 64.9% (excellent in 15 patients, good in 22 patients). Thirty seven patients had sepsis and suspected sepsis. The efficacy was 67.6% in these patients. The rate of improvement in the cases (18 patients) with neutrophil counts under 500/mm3 during the administration among 28 patients who had not responded to prior antibiotic treatment was 67.9%. Diarrhea was found in 1 patient as an apparent side effect likely related to this drug regimen. It appears that combination therapy of SBT/CPZ and AMK was a useful regimen in the treatment of infectious diseases complicated with hematological disorders.