The prandial status of ED patients is often unknown. Because a full stomach predisposes patients to aspiration during a variety of urgent interventions, a method of determining the degree of gastric fullness would be of potential clinical importance. The purpose of this single-blind interventional trial was to determine if bedside ultrasound, performed by EPs, could accurately determine prandial status. We enrolled 20 subjects who were randomized to either a fasting or nonfasting group. Three emergency sonographers scanned each subject in both the supine and right lateral decubitus (RLD) positions and independently recorded their determination of the prandial status both before and after ingestion of water. We found that the technique was specific in identifying a full stomach but only moderately reliable in identifying an empty one. Best results (sensitivity S + 86%, specificity S- 70%, accuracy A+ 78%) were achieved only after water ingestion with the patient in the RLD position. We conclude that bedside ultrasound is of only limited value for determining prandial states in the ED setting.