In considering the effects of oil pollution on British shores, it is also necessary to consider the effect of the emulsifier cleansing which in recent years has inevitably followed it. The reported toxicities of crude oil, emulsifiers and their active constituents are briefly reviewed. Of three major oil-spills in Milford Haven, one in 1962 provided evidence of a marked increase in algal cover following heavy limpet mortalities. The most recent, in January 1967, polluted shores on which the distribution and abundance of common plants and animals was well known, so that the immediate effects could be accurately determined. Effects similar in nature but greater in extent were recorded in Cornwall following the wreck of the `Torrey Canyon' in March 1967. Many of the mechanisms which protect shore animals from natural environmental extremes are ineffective against stranded oil, whilst emulsifiers tend to make it an even greater biological danger.