Echocardiographic strain and strain rate imaging is a new technology enabling more reliable and comprehensive assessment of myocardial function. The spectrum of potential clinical applications is very wide due to its ability to differentiate between active and passive movement of myocardial segments, to quantify intraventricular dyssynchrony and to evaluate components of myocardial function, such as longitudinal myocardial shortening, that are not visually assessable. The high sensitivity of both tissue Doppler (TDI) derived and two-dimensional (2D) speckle tracking derived strain and strain rate data for the early detection of myocardial dysfunction recommend these new non-invasive diagnostic methods for routine clinical use. In addition to early detection of myocardial dysfunction of different etiologies, assessment of myocardial viability, detection of acute allograft rejection after heart transplantation and early detection of patients with transplant coronary artery disease, strain and strain rate measurements are helpful in the selection of different therapies and follow-up evaluations of myocardial function after different medical and surgical treatment. Strain and strain rate data also provide important prognostic information. This Review explains the fundamental concepts of strain and strain rate for both TDI-derived and speckle tracking 2D-strain derived deformation imaging and discusses the clinical applicability with all the major advantages and limitations of these new echocardiographic methods, which recently have become a subject of great interest for clinicians.