Ascariasis is a helminthic infection of global distribution, and intestinal obstruction is its most common gastrointestinal complication. This is a case of a 7-year-old boy admitted to Pediatric Surgery because of intestinal obstruction caused by ascariasis. On admission, the patient presented with colicky abdominal pain, bile-stained vomiting and meteorism. On physical examination, the patient was thin, pale, and dehydrated. An abdominal examination showed distention and diffuse tenderness. After admission, the patient had fecal vomiting and expulsion of worms through the mouth. Laboratory-test results showed leucocytosis, eosinophilia, hypoalbuminaemia, and hypochloremia. Abdominal radiographs and ultrasound studies were indicative of small-bowel obstruction due to roundworms, which led to the performance of an exploratory laparotomy. On bowel exploration, an intraluminal mass, 10 by 6 cm in diameter, consisting of roundworms in the middle third of the ileum was found. A longitudinal enterotomy was performed, and the worms were meticulously extracted manually. Postoperatively, broad-spectrum antibiotics and antihelminthic drugs were administered. Our case of intestinal obstruction caused by ascariasis is the first to be reported in Serbia, according to the Serbian literature.