There have been numerous studies focusing on the assessment of left ventricular mechanical dyssynchrony. These studies are diverse in their purposes, which include more effectively predicting the response to cardiac resynchronization therapy, improving the guidance of the left ventricular lead position, and better prediction of outcome in patients with heart failure. This article reviews the current assessment methods, clinical applications and limitations of left ventricular dyssynchrony indices derived from echocardiography, magnetic resonance imaging and radionuclide imaging in patients with heart failure.