Neutropenia is very common in patients received hematopoietic stem cell transplantation, with median duration of about 14 days. In 2010 update, IDSA recommended Piperacillin/tazobactam as first-line mono-therapy for febrile patients with neutropenia of high risk. In china, the data of piperacillin/tazobactam for febrile neutropenia after hematopoietic stem cell transplantation is very limited.