Ascariasis is one of the most frequent intestinal parasitosis of man, specially in tropical regions where it affects mostly children. The adult worm can migrate through the ampulla of vater and penetrate the bile ducts producing different degrees of obstruction and infection. Ultrasonography is a rapid and simple non invasive procedure very effective for the visualization of the worm in the biliary tree. We present the clinical and ultrasonographic characteristic of biliary ascariasis in five children diagnosed by ultrasonography in our institution during the last nine years.