Evaluation of blunt abdominal trauma is clinically challenging. Diagnostic peritoneal lavage (DPL) and computed tomographic (CT) scanning have become primary diagnostic modalities. We examined the efficacy and role of ultrasonographic (US) studies in the initial abdominal evaluation of blunt trauma patients. Over an 8-month period, patients whose abdominal work-up indicated the need for DPL or CT were evaluated sonographically within the first hour after admission by trauma fellows (PGY-6) with at least 1 hour of theoretical training and 1 hour of practical training. Sonograms considered positive were those showing free peritoneal fluid or organ disruption. Hard copies of the sonograms were evaluated by a staff radiologist without knowledge of the fellows' interpretations or of DPL or CT results. Based on the fellows' interpretation of the real-time sonograms, among the first 163 patients studied were 11 true-positive, 146 true-negative, one false-positive, and five false-negative results. Sixteen patients had intra-abdominal injury documented by DPL, CT, or laparotomy. Ultrasonography was 91% sensitive in detecting the presence of hemoperitoneum. Overall, ultrasonography was 69% sensitive, 99% specific, and 96% accurate in diagnosing abdominal injury. We conclude that emergency sonography on admission can serve as a valuable adjunct to the physical diagnosis of clinically significant hemoperitoneum. It is noninvasive, portable, and accurate in determining the need for further diagnostic/surgical intervention.