From August 1983 to April 1986, 13,368 oiled birds, of 83 species, were found on 665 km of the German North Sea coast including the island of Helgoland. Among these, 1,297 birds were found on Helgoland, 4,938 on the coast of Lower Saxony, and 7,133 on Schleswig-Holstein's coastline. The impact of an oil spill in January 3, 1986 led to an increase in the number of oil victims in the following time. Main number of dead, externally oiled birds found during the investigation time was made up of Eider-ducks with 3,009 (22.5 %), Guillemots with 2,576 (19.3 %), Common Scoters with 1,501 (11.2 %) and Kittiwakes with 1,200 (9 %) individuals. A species comparison on various coastal regions indicated a considerable difference from the overall picture. As a measure for the degree of oil pollution, the oiling rate (number of externally oiled birds as percentage of total number of dead ones found) was a suitable value. The average oiling-rate was 45 % for the whole German coastal area. Regional differences were found (Lower Saxony: 55.3 %, Schleswig-Holstein: 41.7 %, Helgoland: 37.8 %). A comparison on species level of the total number of dead ones with the number of oiled individuals found shows that Auks were with 78.3 % the most affected species in the North Sea. Divers, Grebes, Gannets, Fulmars and Sea-ducks are next most frequently affected. The temporal distribution of oil victims clearly indicates that oiled birds were found in every month on the surveyed transects (mainly during winter from November to April). The oiling-rate from winter 1983184 to 1985186 has risen from 33.6 % to 47.5 %. Dissections of externally oiled birds indicated that 80 % of these also showed oiling-up of their digestive tract. Of 1,791 dead, externally clean, i.e. not oil-foiled birds, 365 specimens showed internal oiling. About 84 % of all Guillemots found dead without evidence of being oiled showed internal oiling. These findings were relatively frequent also for Oystercatchers, Common Scoters, Eider-ducks and Fulmars. 89.3 % of all feather-oilings and beach pollution by oil can be attributed to fuel residues from all types of ships, 54.3 % having been affected by heavy fuel oil (HFO), 3.4 % only crude oil. This clarifies that 91.4 % of the oil pollution recorded were caused by remnants from the operations of ships (remains of fuel oil, bilge and engine oil).