Biorefining is sustainable biomass processing to obtain energy, biofuels and high value products through processes and equipment for biomass transformation. The biorefinery concept has been identified as the most promising way to create a biomass-based industry. Microalgae are classified as promising candidates in biorefinery processes because they are particularly important for obtaining multiple products. This review article describes the biorefinery concept taking into account its different interpretations and comparing it with the traditional biomass transformation processes. It describes the general characteristics of microalgae, and their potential to be used as a raw material in the biorefinery process. The review focuses on the state of the art of products obtained from microalgae for the biofuel industry, mainly for biodiesel production, and the different methods to extract oil for biodiesel production as well as other products. Based on this information, several aspects are suggested to be taken into account for the development of a topology for a microalgae-based biorefinery.