Intertidal soft-bottom assemblages located at high latitudes provide a critical food source for long-distance migratory animals which link biodiversity across distant areas. On the southern Pacific coasts of South America, however, comprehensive information about macrobenthic assemblages at these habitats is lacking. Here we provide an inter-annual estimation of food supply at the southern limit of the Pacific temperate zone within a Site of Hemispheric Importance for the conservation of Arctic breeding shorebird populations during the nonbreeding season. Macrobenthic communities on Isla Grande of Chiloe are dominated by Polychaetes, Bivalves and Malacostraca. Average biomass (4.4-9.6 g ash-free dry weight m(-2)) falls within the values reported for temperate intertidal areas located at around 40 degrees S latitude. While total available biomass within each bay was similar during the three sampling years, the annual contribution of each class varied. The major contributor to zoobenthic biomass (Polychaetes) was indeed one of the main preys for the most abundant shorebird species at Chiloe. Arctic breeding migratory shorebird populations seem thus to encounter a predictable and abundant food supply at high southern latitudes on Isla Grande of Chiloe.