Echocardiography is a powerful noninvasive cardiovascular diagnostic tool. In the emergency room, an outpatient setting, and the intensive care unit, physician-performed point-of-care (POC) echocardiography is particularly important to understand the concurrent pathophysiology of unstable patients. In POC echocardiography, the purpose of examination should be clearly decided in advance by performing careful symptom assessment and physical examination, including heart and lung auscultation. In this article, heart failure, cardiac murmur-, ischemic heart disease, and acute pulmonary artery thromboembolism are selected and overviewed to assess the utility of POC cardiovascular ultrasound. In heart failure, visual assessments of the left ventricular ejection fraction, chamber size ratio, and inferior vena cava diameter are important. An ultrasound lung comet is a very useful finding, suggesting the presence of lung congestion. In patients with a cardiac murmur, the source of the abnormal sound can easily be confirmed by the color Doppler signal in conjunction with chamber size assessment. On the other hand, judgment of the severity of valvular heart disease should be reserved for detailed echocardiography. In acute coronary syndrome, POC echo is extremely important for prompt diagnosis and complication assessment. An understanding of the coronary artery territory and method to detect regional wall motion abnormality in ischemic heart disease is necessary. Papillary muscle rupture and ventricular septal perforation are both fatal complications of myocardial infarction, and they should be kept in mind and pan-systolic murmur should be detected before echocardiography. In acute pulmonary thromboembolism, the right heart size and characteristic wall motion abnormality should be focused on using echocardiography in addition to tricuspid regurgitant flow velocity measurement. Femoral vein ultrasonography with a compression test should be performed for all patients with acute pulmonary thromboembolism to search for potential embolic sources.