Anaphylactic shock caused by sting of crown-of-thorns starfish (Acanthaster planci). A 40s-year-old woman with previous history of injury due to contact with crown-of-thorns starfish, Acanthaster planci, was stung on the right middle finger. After immediately losing consciousness, she died 13 h after injury despite intensive medical treatment. Examination of the respiratory system revealed narrowing due to severe edema of the laryngopharynx, as well as alveolar hemorrhage, eosinophilic infiltration, and extensive neutrophil and eosinophil aggregation in the intravascular lumen of the lungs. Examination of the liver revealed severe diffuse hepatocellular necrosis and extremely high levels of liver transaminases, indicating severe liver damage. Based on these findings, we concluded that she had died from anaphylactic shock induced by circulation of crown-of-thorns starfish venom in the bloodstream. Injurious contact with the spine of the crown-of-thorns starfish can cause severe symptoms as well as systematic reactions, including anaphylaxis. To our knowledge, this is the first case of anaphylactic shock or death caused by human contact with the crown-of-thorns starfish reported in the English-language literature. Although rare, anaphylaxis due to injury by marine animals is potentially fatal. Saving lives requires providing education regarding prevention and enabling prompt response to possible anaphylaxis, including preparation of adrenaline for auto-injection.