Cardiovascular magnetic resonance (CMR) is an accurate, reproducible and well-validated imaging technique for the measurement of left ventricular and right ventricular volumes, function, and mass. In patients who have heart failure, CMR is ideally suited both for the initial assessment of fundamental parameters of cardiac function and longitudinal follow-up. Because of its accuracy, the decision to implement therapeutic measures based on cutoff values for ventricular ejection fraction can be made with confidence. Because the above-mentioned parameters correlate with morbidity and mortality, CMR can be used to estimate the prognosis of an individual patient and to obtain surrogate parameters in clinical trials. The process of ventricular remodeling after cardiac injury and reverse remodeling using medical and interventional therapy can be assessed using relatively small sample sizes, which puts CMR in the forefront of imaging techniques in remodeling research.