Six infectious episodes in patients with acute leukemia, which had been resistant to either CET, CEZ, CBPC or SBPC combined with GM or DKB, were treated with KW-1062 (240-360 mg/ day) combined with CEZ or CBPC. Two cases responded to the combination antibiotics therapy and the other 4 failed to respond. No side effect attributable to KW-1062 administration was noted.