The ultrasound contrast agents significantly improve the chances of diagnostic quality images in routine transthoracic echocardiography. Left ventricular (LV) opacification (LVO) is US-FDA approved indication for improving endocardial border delineation when endocardial border of two consecutive segments are not visualized due to suboptimal window. This chapter covers the principles of ultrasound contrast imaging, technique of left ventricular cavity opacification, use of left ventricular opacification in clinical practice, and uses of MCE in clinical practice. MCE improves sensitivity of stress echocardiography by simultaneous assessment of perfusion abnormalities (which precede wall motion abnormality) and wall motion changes (which are perceived better due to subendocardial defects).