The design of the Health Effects Evaluation Data (HEED) File and the methods used to abstract, code, and computerize Health Hazard Evaluation (HHE) and Technical Assistance (TA) data are described. The following data item categories were included in the final data base design: general report information; hazards; occupations; environmental samples; morbidity and mortality; and laboratory and medical tests. HHE and TA reports are prepared for entry into the data base by personnel trained in chemistry. Computerization of the basic file for the data base is managed by a computer programmer. The data from HHE/TA reports is coded numerically in the HEED File so that analyses such as hierarchical aggregations, frequency counts, cross tabulations, and selection of quantitative levels of categories can be performed. Examples of computer printouts from HHE and TA report are provided along with a listing of potential HEED File users.