SummaryThe roundworm, Ascaris lumbricoides, has been one of the most constant companions since ancient times. It has been described in ancient text from Greece, Mesopotamia, Rome, and China. The detailed life cycle of the ascaris, however, was not known until 1916. The radiological diagnosis was possible because of the mass of worms in children's intestines contrasted against the bowel gas and because the complete intestinal obstruction can cause the typical staircase configuration of air fluid levels on plain radiographs of the abdomen.Ultrasound is most suited to demonstrate the tissue interfaces between the body of the parasite and the lumen of biliary ducts, pancreatic ducts, gallbladder, and other bodily orifices. Because ultrasound units are available in most developing countries, even in small remote countryside medical facilities, it is necessary to know the ultrasonographic findings of this parasitic infection.