Seventy-one neutropenic patients under cytostatic treatment for malignant hemopathies (neutrophil granulocytes less than or equal to/mm3 with feverish episodes in progress (T greater than or equal to 38.5 degrees C) which were probably of an infectious nature were treated according to two antibiotic protocols (piperacillin + amikacin [P + A] or cefotaxime + amikacin [C + A] in a randomized, comparative, prospective study. Of the 71 patients enrolled, 65 could in the end be evaluated for the purposes of this study (36 treated according to the P + A protocol, 29 according to the C + A protocol). In 16 patients the infection was documented bacteriologically. In these cases the percentages of response were, respectively, 77.7% with the P + A and 71.4% with the C + A protocol. The positive clinical results of the two protocols being studied were, considering the entire survey (bacteriologically documented, clinically documented and FUO infections), respectively, 69.4% in the patients treated with P + A and 62.0% in those treated with C + A. The results of the study seem to indicate that the severity of the neutropenia (N.G. less than 500 or greater than 500) does not affect the response to the antibiotic therapy. Modest and transient side effects (hypokalemia and increase of the ClCr) were noted above all in the patients subjected to the therapy with C + A. The results of this study show, therefore, a superimposable effectiveness of the two therapeutic protocols (P + A and C + A) in the empirical treatment of infections in neutropenic patients with malignant hemopathies.