A systematic program of sampling and analysis of blood serum for dioxins, furans, and dioxinlike polychlorinated biphenyls (PCBs) has been initiated in the United States through the National Health and Nutrition Examination Survey (NHANES) program. While such data could potentially be used to estimate population-level changes in human milk lipid concentrations of chemicals, such estimates would depend on understanding the relationship between human blood lipid and milk lipid concentrations of the compounds of interest. For dioxins and furans, extremely limited data in humans currently exist for paired blood/milk samples. These data reviewed in this article, support the hypothesis that, over a population and across time, human milk lipid levels of these compounds generally reflect blood lipid levels. However, these data also suggest that significant variations in these ratios are possible among individuals and at various times.