Dialysis patients receive DEHP exposure from two sources, blood stored in PVC blood bags and tubing used in dialysis treatment. The Environmental Protection Agency (EPA) conducted a preliminary investigation into the suitability of using this group for an epidemiologic study because of their documented exposure to DEHP. As part of this assessment, the Health and Human Services (DHHS), End Stage Renal Disease Medical Information System (ESRD MIS) data base was evaluated to determine its usability in the conduct of such a study. The end stage renal disease (ESRD) patient population was found not to constitute a viable population for an epidemiologic investigation to determine the health effects of DEHP exposure. The bases for this conclusion were the complexities of end stage renal disease and the multiple factors involved in the treatment of the disease. In addition, the ESRD MIS data base was found to lack the completeness, consistency, and accuracy necessary to perform meaningful analyses other than demographic analysis.