The large number of hazardous chemicals manufactured, transported, and stored in the United States creates the potential for significant toxic exposures to workers in industry today. Emergency physicians are likely to be called on to evaluate many of these exposures when they occur in the acute setting. In addition to single-patient exposure, significant potential exists for such exposures in the setting of mass casualties. Emergency physicians need a source of readily available information regarding chemical hazards that can be helpful in the diagnosis and treatment of such exposures. The Material Safety Data Sheet (MSDS) is reviewed herein, with special attention given to the sort of information that can be found on the MSDS and how such information may be clinically helpful to emergency physicians. The significant drawbacks and limitations of MSDS documents are also reviewed. [Greenberg MI, Cone DC, Roberts JR: Material safety data sheet: A useful resource for the emergency physician. Ann Emerg Med March 1996;27:347-352.]