Population estimates of wintering waders on the non-estuarine European coasts are largely based on extrapolated data from relatively small stretches of coast. In Portugal, the previous and only national estimate of waders wintering on the non-estuarine coast was based on just 7.3% of the coastline. In this study we carried out the first survey of waders wintering on almost the whole of the non-estuarine coast of Portugal, in order to improve knowledge on their abundance and distribution and to set a baseline for interpreting future population trends. The majority (96%) of the 198 5x5 km UTM squares, covering 1,096 km of coastline, were counted by observers walking along the shore within 3 h of low tide during the 2009/2010 winter. 6,866 waders, of 13 species, were counted and we estimate the entire Portuguese population at 7,175. Sanderling (2,897-3,027), ruddy turnstone (2,191-2,289) and Kentish plover (581-607) were the most abundant species. Highest wader numbers were found on the north and central (mainly around the Tagus estuary) coasts. The non-estuarine coast holds a significant proportion of the Portuguese winter populations of sanderling (83.6%), purple sandpiper (83.3%), ruddy turnstone (80.1%), whimbrel (33.5%), Kentish plover (17.0%), common sandpiper (16.0%) and Eurasian oystercatcher (15.7%). The study also highlights the international importance of the Portuguese non-estuarine coast for wintering sanderling, ruddy turnstone and Kentish plover, as the counts for these species represent >1% of the relevant biogeographic populations.