Marine Fish and shellfish from Boston Harbor, Salem Harbor, and coastal areas were analyzed to determine tissue concentrations of polychlorinated biphenyls (PCBs). Winter flounder, Pseudopleuronectes americanus , American lobster, Homarus americanus , and several bivalve species were extracted according to U.S. Food and Drug Administration protocol and quantified by gas chromatography as Aroclor 1254. Flounder and lobster collected in Spring, 1986, from Boston Harbor and Salem Harbor were compared to species from coastal sites by analysis of variance.