Abdominal ultrasound is an extremely useful diagnostic tool in the evaluation of the patient with abdominal symptoms. Its advantages include its being noninvasive, portable, and not requiring the use of radiographic contrast material. Sonography has great utility in the diagnosis of abdominal aortic aneurysm. For purposes of diagnosing ectopic pregnancy, ultrasound is best used in conjunction with beta-HCG radioimmunoassay. With respect to the patient with right upper quadrant abdominal pain, ultrasonic scanning has become the method of choice for visualizing the gallbladder and identifying cholelithiasis. The choice of ultrasound for demonstrating urinary obstruction due to ureterolithiasis is somewhat more controversial. Its use should particularly be considered in patients to whom the administration of radiographic contrast material is inadvisable.