Cardiovascular toxicity is one of the most devastating complications of cancer treatment and can arise during or shortly after treatment, or even several years later. Identification of the left ventricular ejection fraction (LVEF) is the most common method to screen for toxic effects on the heart; however, this approach underestimates cardiac damage and additional strategies for the monitoring of treatment-induced cardiotoxicity are being explored. Guidelines for monitoring have been formulated for several cancer treatments; however, appropriate underlying evidence is still largely absent. In this Review, we summarise conventional and contemporary methods for early detection of cardiotoxicity and designate a level of evidence for the basis of each method.