Diet of sea otters (Enhydra lutris) using a haulout site on the north side of the Alaska Peninsula was determined from 50 scats. Dominant prey species were mussels (Mytilus edulis), followed by three species of clams (Siliqua spp., Spisula polynyma, and Tellina lutea), sand dollars (Echinarachnius parma), and helmet crabs (Telmessus cheiragonus). Our results support preliminary findings by Cim-berg et al. (1984) that this sea otter population preys heavily on mussels and that the presence of low caloric value sand dollars in their diet is significant. Coupled with population estimates, our results also provide evidence that this population of sea otters may be declining due, in part, to overdepletion of food resources.