Luminol (Diogenes reagent, 3-Aminophthalhydrazide) is a versatile chemical exhibiting chemiluminescence with a blue glow, when mixed with an appropriate oxidizing agent. Luminol is uesed in forensic investigations to detect trace amounts of blood at crime scenes and in biological researches to detect copper, iron, and cyanides, as well as specific proteins by western blot. Luminol recently displayes promising applications for the treatment of cancer in deep tissues.