Information pertaining to process and job descriptions, analytical data on the concentration of dioxin (1746016) present in materials used in various manufacturing processes, as well as industrial hygiene, and safety and medical data were used to develop potential dioxin exposure estimates of United States production workers for use in retrospective cohort mortality studies. Exposure to dioxin was assigned according to the amount of the product in a given process, the tasks performed by the workers involved in the process, processing conditions, location of the task, and potential contact with dioxin. The first phase of the estimation procedure was dedicated to assessment of the extent of potential exposure at facilities where industrial hygiene data were available, and involved the compilation of uniform task directories and directories for occupational titles. The second phase was dedicated to calculation of the potential dioxin exposure of workers for whom industrial hygiene information was not available. In addition to the compilation of task and title directories, this phase also provided for calculation of the cumulative potential exposure rating values based on occupational histories of the workers. The author concludes that the new exposure matrix is useful in estimating the potential dioxin risk of workers in a Registry cohort and in determining the relative risk of illness due to exposure to the product.