Liquid-liquid extraction by reverse micelles can be used for the separation and purification of proteins from fermentation media. It represents a new downstream process for the extraction of enzymic molecules without any modification to their conformation. The partitioning of alpha-amylase protein between an organic phase, containing a quaternary ammonium salt (TOMAC), and an aqueous phase depends on the parameters of both phases. The ionic strength of the aqueous phase is one of these parameters and it affects the yield of the extraction process. Experiments have been performed at different molar concentrations of NaCl and results have shown that the partition coefficient of the alpha-amylase decreases and the protein extraction profile shifts towards higher pH values as the ionic strength increases.