Neutropenia is reduced white blood cell count. It is a side effect of cytotoxic chemotherapy for cancer and haematological patients. This article aims to help nursing students and qualified nurses who are novices in caring for neutropenic patients to become familiar with the usual body defences against infection; understand how the body’s ability to fight infection is affected by neutropenia; recognise potential sources of infection; and support the patient who is at risk of infection as a result of neutropenia.