One hundred and thirty-nine consecutive episodes of fever were evaluated in 55 patients with hematological disorders during persistent neutropenia. In 121 instances, patients were given trimethoprim-sulfamethoxazole + amikacin (TMP/SMZ + AMI) as an initial antibiotic regimen with clinical success in 51% (i.e. antibiotic treatment was not changed within the first 7 days). Imipenem/cilastatin (I/C) therapy was instituted in: (a) 22 episodes with clinical failure and fever of unknown origin during TMP/SMZ + AMI therapy and (b) 18 episodes with a second fever episode during initially successful TMP/SMZ + AMI therapy. The response rate for all 40 I/C treated episodes was 80%. One neutropenic patient in the whole series died from infectious complications within four weeks from institution of therapy. TMP/SMZ+AMI seems to be a safe and inexpensive "standard" antibiotic regimen in neutropenic patients. I/C appears to have good efficacy when used as secondary therapy after failure with TMP/SMZ+AMI.