Accidents involving toxic releases, explosions, and fires in chemical process industries take a heavy toll of property, human lives, and environment quality. If one could forecast the accidents likely to occur and the damage they were likely to cause, one could devise appropriate strategies to prevent the accidents and contain the damage that did occur. Using this concept, we have developed a computer-automated tool for accident simulation. In this paper the applicability of the concept and the tool is described on the basis of a case study of a typical petrochemical industry. The study reveals that out of eight credible accident scenarios, four would be ’stand-alone’ events, whereas four others would also cause secondary or higher order accidents (domino effects). Of the accidents in the former category, the one as per scenario 8 is the worst as it would adversely impact (within the set limit of 50 % probability of causing lethality) larger areas than the other three such accidents. Among the second category, scenario 1 would be the most undesirable because it would simultaneously cause heat radiation, shock waves, and missile effects over a larger area.