The abdominal ultrasonographic findings of neonates with vomiting and abdominal distension are presented. (1) Hypertrophic pyloric stenosis can be diagnosed if the muscular layer thickness is more than 4 mm with a length exceeding 15 mm at the pyloric ring and the passage of the gastric contents is disturbed. Because gastric dilatation causes the pyloric ring to move to the right posterior portion, the position of the probe must be adjusted accordingly. (2) Intestinal malrotation with midgut volvulus is easily diagnosed based on a positive “whirlpool sign.” In the absence of this sign, passage of the contents of the third portion of the duodenum in the normal direction rules out intestinal malrotation without midgut volvulus. (3) Duodenal atresia involving the second portion of the duodenum will causes enlargement of the left side of the gallbladder. In small intestinal atresia, the enlarged small intestine above the atresial site will have a common boundary with the collapsed gastrointestinal tract below this site. (4) Necrotizing enterocolits presents as multiple hyperechoic dots in the edematously thickened wall of the gastrointestinal tract. The dots represent foci of intestinal pneumatosis. Gas in the portal vein adjacent to the liver will also present as hyperechoic dots on B-mode, whereas gas trapped in the liver are visible as a ventral hyperechoic area of the liver parenchyma. Hyperechoic dots and portal vein gas are characteristic of the early stage of necrotizing enterocolitis. These findings can be detected by ultrasonographic examination while it is impossible to do so by X-ray.