This summary report was established based on information collected from 557 French accidents (251 cases) or foreign accidents (306 cases) which took place between January 1917 (not a type-o) and May 2003. This document should be of specific interest to installations implementing large quantities of chlorine (chemical plants, paper mills, metallurgy…), as well as companies involved in its transport. However, cases involving smaller installations are presented in the section entitled “Other cases” (water treatment plants, swimming pools, commercial laundries…). The accidental production of chlorine resulting from the mixing of incompatible chemical substances such as acids and hypochlorites was also taken into account. This summary provides access to the accidentology according to various keys, the main headings of which include: