San Francisco Bay was placed on the State of California’s 303(d) list of impaired waters in 1998 as a result of elevated concentrations of dioxins and furans (commonly referred to as ‘dioxin’) in fish. RMP studies of contaminants in Bay sport fish conducted every three years since 1994 have found that dioxin concentrations have remained unchanged over this time period and in some species, continue to greatly exceed screening values for human consumption. Our understanding of dioxin in the Bay is extremely limited, however, and improving this is a necessary first step in reducing concentrations in Bay fish and resultant health risks to fish-eating humans and wildlife.