The U.S. EPA's Office of Toxic Substances (OTS) maintains a unique capability for monitoring human exposure to potential toxic substances through the National Human Adipose Tissue Survey (NHATS). The primary focus for NHATS has been to document trends in human exposure to environmentally persistent contaminants, specifically, organochlorine pesticides and polychlorinated biphenyls (PCBs). The report deals specifically with the measurement of polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in composited adipose tissue samples from the FY82 NHATS repository. The results of the study demonstrate that the EPA NHATS program is an effective vehicle for documenting the exposure of the general U.S. population to PCDDs and PCDFs. The analysis of the 46 composite samples prepared from the fiscal year 1982 NHATS repository establishes the prevalence of the 2,37,8- substituted tetra- through octachloro-PCDD and PCDF congeners in the U.S. population. The PCDD and PCDF levels are comparable to data presented from other studies that focus on samples collected in upstate New York, Canada, and Sweden.