Book excerpt: Associated with both acute kidney injury (AKI) and cardio-renal syndromes (CRS), new biomarkers represent both a popular area of investigation and a new opportunity for advancement of therapy. This book contains the resolutions of the most recent ADQI conferences on biomarkers in AKI (Dublin) and on cardio-renal syndromes (Venice). The first part answers specific questions about new biomarkers and their use and utility in AKI: What are the most suitable candidate molecules and physiologic measures, how solid and evidence based is the discovery phase? How can we incorporate the new biomarkers in the AKI conceptual model describing the evolution from susceptibility to insult, decreased GFR and organ death? Even if we have a positive biomarker pattern and we can identify patients at risk or patients with early or even subclinical AKI, how is this information affecting our clinical behavior and practice? The second part is dedicated to the appraisal of the current knowledge about the pathophysiological mechanisms involved in different forms of CRS: it contains contributions on the state-of-the-art knowledge and practice of CRS, particularly focusing on the pathophysiology of the five subtypes. Acute and chronic mechanisms of damage are explored in depth, with particular attention to the primacy of organ involvement and the subsequent pathways of organ crosstalk.Presenting the most recent research in the field of biomarkers, AKI and CRS, this publication is an important educational tool for advanced investigators and clinical experts, but also for students and fellows.