The ever increasing demand for oil, coupled with the reduction in reserves, is increasing emphasis on finding new oil deposits and recovering more oil from known reserves since half to two thirds of all of the oil discovered to date is still in the ground and not recoverable by present technology. There are, however, microbiological techniques that could be of value in extending the time before alternatives to oil as the major energy source are required. Two will be discussed here – geomicrobiological prospecting and microbial enhanced oil recovery (MEOR).