We treated 20 febrile episodes in 14 patients with granulocytopenia under 1.0 x 10(9)/L. 6 episodes were pretreated, in 14 Imipenem/Cilastatin was the initial therapy. The age was between 36 and 78 years, mean 57 years. Predominant underlying disease was acute leukemia. 8 out of 20 episodes became afebrile. Counting only proven bacterial infections the response rate was 6 out of 12. There was a statistical difference between not pretreated and pretreated patients. The treatment had no success in the latter. There was also a significant difference between febrile episodes of patients with granulocytes increasing under treatment to those remaining unchanged. 5 of 6 of the first group but none of the 9 episodes of the second group resolved. 7 patients died while on treatment between the 9th and 32nd day after therapy had started. There was no connection between the Imipenem treatment and the deaths. Tolerance of therapy was good. The most common side effect was nausea, which was reversible with reduction of the infusion rate. Most important advantage of imipenem is the easy handling and the low inconvenience to the patient. We had only moderate efficacy in our series.