Imipenem/cilastatin sodium (IPM/CS) and amikacin sulfate (AMK) were administered to 111 patients with severe infections complicating hematological disorders. Of the 111 patients, 93 were included in the present analysis of efficacy and 108 in that of safety. Twenty patients were evaluated as excellent, 37 as good, 8 as fair, and 28 as poor, with an overall rate of effectiveness of 61.3% (57/93). The synergistic interaction of IPM and AMK against clinical isolates (6 strains) was assessed in vitro using the checker board technique. Synergistic and additive effects were observed in 66.7% and 33.3% of the samples, respectively. Side effects were observed in 9 patients and abnormal laboratory test results in 2. These disappeared or returned to normal values after completion of therapy or discontinuation of IPM/CS and AMK. From the above findings, IPM/CS with AMK is considered to be a useful antibiotic combination for the treatment of severe infections complicating hematological disorders.