Petroleum perhaps is one of the most important substances in the modern society due to its wide use in the most diverse productive sectors. Besides serving as raw material to the production of plastics and other compounds, it is the fuel source used in the production of electric energy, in industries and in different transport sectors. However, the ecosystems located in areas of extractions, processing and distribution of petroleum end up being highly susceptible to the direct and indirect impacts of these activities, as well as those located in their transport route. As the large extraction fields are located in coastal areas, these environments are, generally, the most affected, although other ecosystems also suffer influence of petroleum activities. Oil spills and leakages provoke immediate effects into the environment, easily viewed by the generalized mortality of animals and consequent ecosystems losses, but also provoke more persistent effects, such as alteration of the animals behaviour and permanence of compounds derived from petroleum in the food webs. Accidents with petroleum are unpredictable and the resources needed to minimize their impacts, often, are not liable to an immediate application. This book discusses different prevention methods as well as environmental and ecological impacts oil spills have.