Mechanical circulatory support is, nowadays, a well established treatment modality for end stage heart failure. Patients candidate for cardiac transplantation who decompensate while awaiting graft can be supported by long-term left ventricular assist devices (long-term LVAD). These devices are intracorporeal pumps, expensive and complicated to install, but offer the advantages of a high cardiac output and a good patient mobility. Echocardiography is usually applied to any kind of LVAD to accomplish: preoperative evaluation to exclude contraindications, intraoperative when circulatory support starts to assess left ventricular (LV) filling and unloading, postoperative evaluation during intensive care unit course to prevent hypovolemia, cardiac tamponade and right ventricular failure, controls during assistance for suspected device malfunction. Short-term devices are utilized as acute support after the initial resuscitation of the patient. These devices are bedside extracorporeal pumps, less expensive and less complicated to install. They provide a brief but sufficient time to wait patient recovery (''bridge to recovery'') or to evaluate further therapies (''bridge to long-term device'' or ''bridge to transplantation''). Echocardiography has an important role during implantation to guide cannulae positioning, to prevent insufficient LV unloading, to detect echo contrast enhancement with blood stagnation and intracardiac clot formation, to titrate pharmacologic support, and to assess myocardial recovery.