When making prescribing decisions, it is important for healthcare professionals to remember that individual patients may respond differently to medicines. For example, some patients may experience a therapeutic benefit while others may experience an adverse drug reaction. The aim of personalised medicine is to tailor treatment based not only on a patient’s clinical factors, but also on their genetic profile. Pharmacogenomics is a branch of personalised medicine that is concerned with how differences in people’s genomes affect their response to medicines. Pharmacogenomic testing, which recently has become less expensive and increasingly available, can inform nurses’ prescribing decisions and improve patient outcomes. This article discusses personalised medicine and pharmacogenomics, including how pharmacogenomic testing can optimise medicine prescribing, and explains the role of nurses in the process.