The environmental contamination resulting from the B-52 accident in 1968 at Thule was studied by scientific expeditions in 1968, 1970 and 1974. The contamination was mainly confined to the marine environment, where Pu was preferentially located in the sediments and the benthic fauna. Pu concentrations down through the sediment layers decayed exponentially with a half-depth of 1-2 cm. The horizontal distribution of the Pu may be described by an exponential expression: mCi239,240Pu km-2 = 460e-0.28R or by a power function: mCi239,240Pu km-2 = 370 R-1.2, where R is the distance in km from the point of impact. The inventory of 239,240Pu in the marine environment from the accident was estimated at 25-30 Ci. The amount of 238Pu was .apprx. 0.5 Ci. The bottom animals, such as worms and molluscs, showed a horizontal distribution of radioactivity similar to that of the sediments. From 1968-1970 the 239,240Pu concentrations in the biota decreased by an order of magnitude, since 1970 the decrease was less evident. In 1970 and 1974 there were no indications of increased Pu concentrations in surface seawater or in sea plants or zooplankton. Higher animals such as fish, seabirds and marine mammals showed no tendency to increasing Pu levels since the accident.