Cardiovascular (CV) toxicity is defined as the development of structural and/or functional abnormalities in the heart or vascular system resulting from the exposure to noxious substances, physical agents and/or medical treatments. It can occur due to the exposure to traditional CV risk factors (proatherogenic dyslypidaemia, homocysteine, tobacco smoke), pathogenic microorganisms and their toxins, medications, illicit drugs, radiation, etc. Particular interest has been recently dedicated to CV toxicity resulting from the exposure to environmental pollution (fine particulate matter, nitrogen dioxide, ozone), cancerCancer therapy-related CV toxicity (antineoplastic medications and anticancer immunotherapy), and rare toxic effects of other medications and vaccines. This chapter discusses the definition, etiology, clinical manifestations, and diagnostic assessment of CV toxicity, with a particular focus placed on the role of circulating biomarkers in the diagnosis, risk stratification and prognosis of patients affected by CV toxicity. It provides a detailed overview of the role of traditional and emerging biomarkers of myocardial injury and remodeling, along with biomarkers of inflammation and oxidative stress and biomarkers of vascular endothelial dysfunction, damage and injury. The chapter adopts an integrative approach to evaluating CV toxicity by combining the findings from biomarkers, electrocardiographic alterations, multimodal imaging, and other diagnostic assessments. The detailed understanding of pathophysiological mechanisms and signalling pathways reflected by circulating biomarkers, alongside the requirements for their measurement and the clinical interpretation of their values, holds significant diagnostic and prognostic importance for researchers and clinicians alike.