The study of accident case histories is of utmost importance in preventing the repetition of the same accidents or of accidents with the same causes. This is especially true in the case of runaway reaction accidents. In the study of accident case histories, the following considerations should be addressed: description of the process and chemistry involved; description of the circumstances and consequences; identification of the causes with special attention to the chemistry; review of the relevant literature to determine if the same accident has occurred before; comparison of the circumstances with other accidents or incidents where the same cause or chemistry was involved; lessons learned-considerations and factors which provide warnings to prevent the same type of accident from occurring again. In this paper, this approach is applied to the following accidents: the Seveso accident (1976); the Bhopal accident (1984); the Griesheim accident (1993); the frequent phenol + formaldehyde runaway reaction; the accidental bulk polymerization of reactive monomers with consideration of vinyl acetate and acrylic acid. It will be shown that the study of accident case histories can greatly reduce the rate of occurrence of runaway reaction accidents.