The National Fire Protection Association (NFPA) rankings for health flammability, reactivity, and special hazards have been considered the basis for calculating the risk indices of materials in transportation as they have adopted the United Nations criteria for toxicity and corrosivity, which also addresses hazards in transportation to some extent. Bing these NFPA rankings a method has been developed to calculate the risk indices of chemicals during transportation. Other factors such as quantity of material moving, distance between the point of release and population, rate of dispersion and probability of an accident were also considered in this paper for calculating the transportation risk index of a chemical. This index can be used as a guide for assessing the potential hazards of a chemical during its transportation. (C) 2004 American Institute of Chemical Engineers Process.