Biomarkers have an increasingly important clinical role in managing patients with heart failure as well as those with kidney disease, both common conditions with generally poor prognostic outcomes and huge impacts on healthcare economics. For patients with chronic heart failure, biomarkers have become centre place in streamlining diagnostic pathways as well as identifying those with worse prognosis. There is much interest in the role for biomarkers in identifying patients at risk of acute kidney injury, although a number of these currently remain as research tools or are in the early stages of evaluation in clinical practice. Patients with cardiorenal syndrome represent a particular challenge to the clinician, and recent studies have suggested a valuable clinical role for certain biomarkers in this setting, either on their own or in combination. This paper will focus on biomarkers with a current clinical role in patients with cardiorenal disease (natriuretic peptides and neutrophil gelatinase-associated lipocalin), although brief reference will be made to other biomarkers with potential future application.