Antimicrobial resistance (AMR) is a global threat and a considerable public health issue. AMR makes it challenging to treat infections in patients with cancer, particularly those who are immunosuppressed and those who receive cytotoxic therapy (chemotherapy). The aim of antimicrobial stewardship (AMS) is to prevent the overuse, misuse and abuse of antimicrobials. Advanced nurse practitioners working in acute oncology need to consider the growing risks posed by AMR and apply AMS in their prescribing practice. This article uses reflection on a fictional case study to discuss important considerations in oncology nurse prescribing practice, including the need to optimise antimicrobial treatment for individual patients and promote the responsible use of antimicrobials generally.