Ascariasis of the gallbladder is a very rare presentation. We report a case of a 15-year-old boy who presented with complaints of pain in the abdomen, vomiting, pruritus, and fever on-and-off for 10 days. On radiological examination, an ultrasonography of the abdomen showed a dilated gallbladder with multiple linear echogenic, tubular, parallel lines inside the lumen of the gallbladder, common bile duct and intrahepatic biliary radicles. The zigzag and coiling movement of a worm was noted in the lumen of the gallbladder on real time B-mode ultrasonography. The patient was successfully treated with an anthelminthic drug. On follow up no evidence of the worm was noted in the gallbladder or common bile duct lumen.