A 3-year-old boy presented at the emergency room with abdominal pain, nausea and non-bilious vomiting. Physical examination revealed moderate symptoms of dehydration, a tender and slightly extended but soft abdomen and active peristalsis. With the working diagnosis of viral gastroenteritis the boy was admitted to the hospital for rehydration therapy by nasogastric tube. After a few days an abdominal X-ray was taken because of bilious vomiting and persistent absence of defecation. Connected foreign bodies were seen in the small intestine. These appeared to be 3 magnetic toy parts. Laparotomy showed that all symptoms were due to a volvulus of the small intestine around a fistula caused by entrapment of the intestinal wall between attracted magnets. Magnetic construction toys can be bought in toy stores in the Netherlands. Vigilance should be exercised with magnetic toys, because ingestion of multiple magnets can cause potentially life-threatening bowel complications.