In April and May 1991 a group of ornithologists, sent by the International Council of Bird Preservation (ICBP) and supported by the Royal Society for the Protection of Birds (RSPB), the Dutch Foundation Working Group International Wader and Waterfowl Research (WIWO) and the Saoudi National Commission for Wildlife Conservation and Development (NCWCD), visited the Saoudi Arabian Gulf coast in order to assess the impact of the oil, spilled because of the war by Kuwayt oil springs, on migrating waders and seabirds. The rich environment of the Persian Gulf is little studied but is known to hold large populations of five tern species, the near-endemic and slowly declining Socotra Cormorant and, among others, Dugongs, sea-turtles and dolphins. The oil covered about 200 kilometers of the coast, south to the peninsula of Abu Ali (figure 1). Large intertidal mudflats were covered by oil as well and became useless to waders and other birds. By carrying out high tide and low tide counts in three different study areas -one completely oil fouled, one without oil and one ”in between” (figure 1)- information was gathered about numbers and distribution of waders. Moreover, oilscore percentages were gathered in the field on herons, waders, gulls and terns and waders were captured and ringed to get detailed information about the possible effects of oil fouling. From the middle of May onwards tern colonies were visited and counted. The species which appeared to be most affected were Great Crested and Black-necked Grebe and Great and Socotra Cormorant. On basis of counts of corpses along the coast an estimated 20,000-30,000 birds have died, including about 12,000 Black-necked Grebes. From January onwards several hundreds of birds were brought in to the quickly improvised bird hospital, mainly Great Crested (200) and Black-necked (240) Grebes and Great (400) and Socotra (600) Cormorants. Of the two latter species approximately 200 and 350 respectively could be released after being treated (and ringed), of the former two species virtually none. The oil quickly became non-toxic but remained dangerous to birds because of the high ambient temperatures. Although most adult terns were just slightly affected, juveniles of Crested and Lesser Crested Terns, gathered together on the beach in criches, were seen becoming oiled even before fledging. Over 75,000 pairs of breeding terns were counted in five colonies, the most numerous being Bridled and Lesser Crested Terns. The still continuing oil spills are of great concern and it is hoped that the Saoudi government will take action and protect its coastal habitats before it is too late.