This paper reviews some of the field aspects of hydrocarbon bacteriology in the marine environment. The first section recapitulates the current position with regard to the input of polluting oil into the sea and the main environmental factors which govern the rate of oil breakdown. The second deals with the 1991 oil spill during the Gulf War and what is known about the bacteriology of that area, together with some recent data from Japan. Thirdly a critical review of the theory and practise of bioremediation as applied to contaminated beaches in several parts of the world leads to the conclusion that there are still a lot of unknown variables that must be better understood before the method can be of widespread use. Finally a short review of gaseous hydrocarbons in the sea suggests that methane from petrogenic or biogenic sources is of both practical and theoretical interest and importance for the future.