Hydrogen peroxide is a readily available clear, odorless liquid that is commonly used as an irrigant for superficial wounds. It is not widely thought of as a poison; however, it may rarely be the cause of accidental death. A case of fatal oxygen embolism in a child after ingestion of hydrogen peroxide is reported. A total of five similar cases have been previously described. Morbidity and mortality have also been reported with the use of hydrogen peroxide in hospitals. Gastric catabolism of hydrogen peroxide produces oxygen and water. When the amount of oxygen evolved exceeds its maximal blood solubility, venous embolization occurs. Hydrogen peroxide should not be considered to be innocuous; it should neither be ingested nor used in situations where the evolved oxygen gas cannot dissipate freely. The ubiquitous nature of household peroxide and its erroneous benign reputation suggest that child-resistant containers are in order. A protocol delineating the medicolegal investigation and postmortem examination of fatalities caused by the ingestion of this substance is offered.