The BLEVE (boiling liquid expanding vapor explosion) can occur with almost any liquid contained in a closed vessel, at a temperature well above its boiling point at atmospheric pressure. If the vessel fails, the vapor will expand and the superheated liquid will undergo a quick flash vaporization; the associated sudden increase in volume will originate an overpressure wave, that is, an explosion. This explosion can occur with any liquid, be it flammable or not, but if flammable then it will be followed by a fireball. The couple BLEVE-fireball can occur both in fixed plants and in transportation by rail or road. Knowledge of this type of accident has improved significantly during past decades, and measures to reduce its risk have consequently improved. Nevertheless, it still occurs from time to time and its consequences can still be very severe. In this chapter, a description of this phenomenon is provided, together with a review of the diverse methods employed to evaluate the mechanical, thermal and fragment rocket effects associated with this accident. Some recommendations concerning the management of these types of emergency are also provided.