Results of 54 sonographic examinations of patients referred for suspected or known small intestinal obstruction were retrospectively correlated with surgical findings, and the diagnostic value of sonography regarding presence, level, and cause of obstruction was compared with that of plain abdominal radiography. The diagnosis of obstruction was correct in 89% of cases with sonography and in 71% with plain radiography. The level of obstruction was correctly predicted in 76% of cases with sonography and in 51% with plain radiography. The cause of obstruction was correctly predicted in 20% of cases with sonography and in 2% with plain radiography. The authors conclude that use of sonography in evaluating patients with bowel obstruction may be helpful in confirmation of the presence of obstruction, in determination of the level of obstruction, and in identification of the cause of obstruction.