Great Lakes (GL) sport fish consumption is a potential route of exposure for environmentally persistent organochlorine contaminants, which may have human health effects. In this report, relationships are explored among individual congeners in a large cohort of frequent and infrequent GL sport fish consumers. Blood samples were obtained in 1993-1995 and analyzed for 1,1-bis(4-chlorophenyl)-2,2-dichloroethene (DDE) and for 62 noncoplanar polychlorinated biphenyls (PCBs), 4 coplanar PCBs, 8 polychlorinated dibenzo-p-dioxin (dioxin), and10 dibenzofuran (furan) congeners. All GL fish eaters and referents had detectable levels of DDE, total noncoplanar PCBs, total coplanar PCBs, total dioxins, and total furans. Noncoplanar PCBs were higher in GL sport fish consumers than in a referent population from the same geographic area, were associated with GL sport-caught fish (GLSCF) consumption, and varied significantly by Great Lake. DDE, lower chlorinated dioxin and furan toxic equivalents (TEQs), and coplanar PCB TEQs were positively associated with noncoplanar PCBs but were not associated with GL sport fish consumption independent of PCB level. Highly chlorinated dioxin and furan congener TEQs were not significantly associated with noncoplanar PCBs or GL sport fish consumption, suggesting that participants were acquiring some of these TEQs from a source other than GLSCF. In epidemiologic studies, it may be important to include populations with higher organochlorine exposures as well as background exposures and to consider the effects of individual congeners or mixtures of congeners on health outcomes.