Cases of ingesting button batteries by children are not common clinical situations in forensic medicine. Although it can be a cause of death when associated with digestive perforations, no cases of sudden death have been reported in the literature. We report the case of a 17-month-old girl who presented at home with haematemesis, followed by failed cardiopulmonary resuscitation. The child had been treated on two occasions for nasopharyngitis, 14 and 18 days prior to her death. The post-mortem scan revealed a radio-opaque foreign body in the oesophagus. The autopsy revealed the presence of a round button battery, 20 mm in diameter, blocking the lumen of the oesophagus in its upper third, associated with two parietal oesophageal ruptures opposite each other. There was limited digestive haemorrhage, but above all significant bronchial inhalation of blood. Toxicology analyses showed slightly increased blood levels of the heavy metals of which the battery was composed (lithium, chromium, manganese and molybdenum). The anatomopathological analyses confirmed the recent nature of these ruptures. Ingestions of button batteries localised at the level of the oesophagus are the cases linking to the highest risk of complications, particularly for batteries with a diameter of more than 20 mm and in children under the age of 4. The main difficulty in such clinical situations is identifying when the ingestion occurred, as more often than not, no witnesses are present. We discuss the advantages of anatomopathology and toxicology examinations targeted towards heavy metals in these forensic situations.