This OTA background paper evaluates the current state of knowledge and assesses the potential of bioremediation for responding to marine oil spills. Our basic message is a dual one: we caution that there are still many uncertainties about the use of bioremediation as a practical oil spill response technology; nevertheless, it could be appropriate in certain circumstances, and further research and development of bioremediation technologies could lead to enhancing the Nation’s capability to fight marine oil spills.