Information about shorebirds is essential for predicting the impact of natural and human-mediated changes on their populations. Aerial and terrestrial surveys were performed to characterize shorebird abundance, spatial distribution and assemblage composition at Samborombón Bay, Argentina, during different tide levels and seasons. Approximately 60,000 shorebirds were observed using the intertidal flats. Highest abundances occurred during austral summer, autumn and spring when Nearctic migrants dominate the assemblage. Significant percentages (> 1%) of the populations of three Nearctic migrants [American Golden-Plover (Pluvialis dominica), Hudsonian Godwit (Limosa haemastica), and White-rumped Sandpiper (Calidris fuscicollis)], one Neotropical migrant [Two-banded Plover (Charadrius falklandicus)], and two resident species [American Oystercatcher (Haematopus palliatus) and Black-necked Stilt (Himantopus mexicanus)] were estimated. Large numbers of Semipalmated Plovers (C. semipalmatus), Rufous-chested Dotterel (C. modestus), and Ruddy Turnstones (Arenaria interpres) were also recorded. Management measures aimed at maintaining healthy, viable populations should address species needs during all four seasons focusing on the southern and central sectors of Samborombón Bay, which are the most important feeding areas for shorebirds.