Acceptance of intensivist-performed ultrasound in the United States has lagged that in Europe, but now, largely driven by their success in facilitating vascular access, reducing procedural time, and avoiding complications, these devices have become ubiquitous in ICUs. Indeed, many intensivists now feel that, for nonemergent central venous catheterization, the standard of care requires real-time ultrasound guidance. Yet, ultrasound offers great potential in other critical care realms. Intensivists who have acquired the necessary equipment and learned to use it to place central venous catheters are now aiming their probes at venous thrombi, pleural effusions, abdominal fluid collections, aortic aneurysms, thick-walled gallbladders, paradoxically moving diaphragms, and the heart. Intensivists quickly discover that they can exclude hydronephrosis in a patient with urosepsis more expeditiously by turning on their own ultrasound machine than by ordering a radiology-based examination that will be interpreted many hours later. More subtly, the patient may benefit from a lower threshold for performing an ultrasound examination than for ordering an alternative test. As an example, take the mechanically ventilated patient with ARDS who has some deterioration in gas exchange or hemodynamics. When should the clinician order a portable chest radiograph to exclude pneumothorax? Because it takes only 5 min to accurately exclude pneumothorax with a hand-held ultrasound, the intensivist is more likely to perform that test early or when the clinical probability for pneumothorax is small, rather than waiting for clinical signs to progress in order to “justify” ordering the radiograph.