Marine and estuarine habitats near urban or industrialized regions are vulnerable to contaminated runoff. Harbor seals (Phoca vitulina richardsi), which occur throughout much of the northern hemisphere, are useful mammalian biomonitors because they feed, reproduce, and rest near or on shore and are high-level trophic consumers. They have often been monitored for contaminants in Europe (Wagemann and Muir 1984). To date, no studies have been reported on contaminants in harbor seals from industrialized areas of Alaska. In the vicinity of Anchorage, Alaska's largest urban and industrial city, harbor seals are sedentary and limited to coastal waters; some movements have been documented but there is no evidence of extensive migrations. Although some harbor seals in the Kodiak Archipelago move up to 100 km along the shore, strong fidelity to specific haulout sites is more common (Pitcher and Calkins 1979). These seals eat mainly non-migratory fishes and octopi. Harbor seal numbers have declined substantially from unknown causes in the southern part of the Kodiak Archipelago. The Alaska Department of Fish and Game (ADF&G) suggested that the decline is a trend for the entire Kodiak region and other Alaskan waters. Contaminants have been suggested as a possible reason for the precipitous decline of Steller sea lions (Eumetopias jubatus) in the region (Braham et al. 1980), and were suspected in the decline of harbor seals. In this study, harbor seals were sampled from throughout the Kodiak Archipelago to determine concentrations of certain metals, metalloids, polychlorinated biphenyls (PCBs), and organochlorine pesticides, and to determine if these concentrations varied by sex or accumulated with age. All seals were collected within 75 km of Cook Inlet, an estuary next to Anchorage. The targeted elements or compounds were known to be toxic to a wide spectrum of organisms (e.g., MARC 1980; Eisler 1986).