Novel fermentation processes characterized by the simultaneously production and separation are known as Extractive Fermentations. Liquid-liquid extraction is a separation technique that can be used for this purpose. These processes are widely used in the chemical industry owing to its simplicity, low costs and ease of scale-up. However, most extraction processes include the use of organic solvents, which have both environmental and occupational risks associated to their use. This makes these extraction systems inappropriate for the development of environmental-friendly technologies. In this context, the use of aqueous two-phase systems based in Ionic Liquids appears as a successful method for the bioproducts purification. This book reports an integrated study on the use of ILs as alternative solvents in Fermentation processes. The purification capacity of a large set of ILs was investigated, using different biomolecules as models with distinct structural complexities. A biocompatibility and toxicological study was also assessed in this work.