Backgrounds: We have shown that contrast echocardiography (CE) is useful for the assessment left ventricular (LV) function and clinical diagnosis. However, there has been no data about clinical usefulness of contrast echocardiography in patients who were admitting intensive care unit (ICU) in Korea. The aim of this study was to evaluate the impact of contrast echocardiography in critical care patients on assessment of ventricular function and clinical diagnosis. Methods: We prospectively enrolled 84 patients (mean age 54 짹 17) from 10 general hospitals in Korea with technically difficult echocardiographic studies who received intravenous contrast Definity (Lantheus Medical Imaging, Billerica, Massachusetts) in critical care patients. Of the 84, 34 (40%) patients were admitted in CCU, 15 (18%) were MICU, and 35 (42%) were SICU. 36 (43%) patients had mechanical ventilator care. Portable echocardiography was performed 50 (60%) patients. Quality of studies, number of visualized LV segments, estimated ejection fraction, ability to identify LV wall motion abnormality, visualization of LV apex, right ventricular (RV) function, any changes in diagnostic procedure and treatment strategy were compared before and after contrast. Results: After contrast injection, the percent of poor or uninterpretable studies decreased from 28.3% to 2.1% (p < 0.001), technically adequate studies increased from 23.5% to 90.6% (p < 0.001). Before contrast, 11.1 of 17 LV segments were seen, which improved after CE to 16.4 (p<0.001). An ability to visualize LV apex was increased from 14.5% to 91.5% (p<0.001). A significant impact of CE on management was observed: any changes in diagnostic procedures after CE was 25.9% of patients and treatment plan was altered in 30.6% of patients. Conclusions: The utilization of CE in critical care patients improves endocardial visualization and impacts cardiac diagnosis and patient management.