Fossil fuel depletion and attempts of global warming mitigation have motivated the development of biofuels. Several feedstock and transformation pathways into biofuel have been proposed as an alternative to usual fuels. Recently, microalgae have attracted a lot of attention because of the promise of reduced competition with food crop and lowered environmental impacts. Over the last years, several Life Cycle Assessments have been realised to evaluate the energetic benefit and Global Warming Potential reduction of biofuel and bioenergy produced from microalgae. This chapter presents a bibliographic review of fifteen LCA of microalgae production and/or transformation into biofuel. These studies differ often by the perimeter of the study, the functional unit and the production technologies or characteristics. Methods for the environmental impacts assessment and the energy balance computation also diverge. This review aims at identifying the main options and variations between LCAs and concludes by some recommendations and guidelines to improve the contribution of an LCA and to facilitate the comparison between studies.