The efficacy of piperacillin/tazobactam (PIPC/TBT) in combination with gentamicin was assessed as empirical therapy in 44 febrile neutropenic patients with haematological malignancy. A favourable response to therapy was seen in 67% patients overall and in 57% of patients with microbiologically documented infection. PIPC/TBT demonstrated good clinical and in vitro activity against isolated pathogens, particularly Gram positive cocci such as Staphylococcus epidermidis. The MIC of both Gram positive and Gram negative pathogens to PIPC was reduced in the presence of TBT. PIPC/TBT plus gentamicin is a safe and effective combination for empirical therapy in febrile neutropenic patients, even in a unit with a predominance of Gram positive infections.