During the Bremerhaven Workshop, sediment samples from 2 pollution gradients in the North Sea were tested in a 10 d static bioassay with infaunal amphipods. One gradient was downstream from a former drilling site, the second was offshore of the Elbe-Weser plume in the German Bight. Four participating laboratories used basically the same technique to test sediment toxicity with 1 of 3 different amphipod specles: Rhepoxynius abronius, Corophium volutator or Bathyporeia sarsi. The measured endpoints were mortality and sublethal effects, including the inability to reburrow after exposure, avoidance and immobilisation. Results show that sediment samples from the stations on each gradient closest to contaminant sources were toxic to nearly all test species. Samples from other stations only caused mortality in the tests with C. volutator.