Inhibition of settlement of the larvae of the barnacle Balanus balanoides was observed to result from experimental applications of weathered Ekofisk crude oil to bare rock surfaces in the intertidal zone of a Norwegian fjord. The degree of inhibition appeared to be related to the oil concentration applied. B. balanojdes settlement on heavily oiled surfaces was initially less than 1 % of that on unoiled squares; squares initially receiving '/a this amount of oil showed only a 50 % reduction in barnacle settlement.