As a result of better treatment options for malignant cancer, the cardiovascular side effects of such therapies have increasingly come into focus in recent years. The new cardiological subspecialty of oncocardiology is developing strategies to prevent and/or detect those effects early in order to treat them in a timely and adequate manner. The diagnosis of cardiotoxic effects is based mainly on imaging and specific biomarkers. Echocardiography has become the main imaging technique due to its wide availability. In addition to quantitative determination of left ventricular function using two-dimensional methods, three-dimensional methods offer better precision and less variability in the detection of cardiac dysfunction. Furthermore, the analysis of the global longitudinal strain (GLS) reveals even subtle changes in left ventricular function and thus detects very early damage before left ventricular ejection fraction drops. Various biomarkers have been tested recently for their potential to detect cardiotoxicity. Cardiac troponins are currently the best investigated biomarkers and certainly have the highest impact. Due to contradicting results, the importance of natriuretic peptides has not yet been conclusively clarified. Results for myeloperoxidase are promising, as are the results for circulating microRNAs, which still mainly derive from experimental data. In this context, further studies still need to show the value of these in everyday clinical practice.