Micellar aggregates are known to be useful for the selective isolation of biologically active materials such as amino acids, proteins, and enzymes sparsely dispersed in aqueous mixtures. In this work, the effects of pH, the type of added salt and its concentration in the excess aqueous phase on the back extraction efficiency of bovine serum albumin (BSA) using a reverse micellar system, of which the organic phase contains sodium di-(2-ethylhexyl) sulfosuccinate (AOT) and iso-octane, were extensively examined. In this effort, BSA solubilized in the reverse micelles by means of the phase-transfer method was back-extracted by bringing an excess aqueous phase into contact. When 1:1 salt such as KCl or NaCl was added, BSA effectively back-extracted to the excess aqueous phase at higher pH values than its isoelectric point pI. In case of NaCl, the molar ratio of water to surfactant in the organic phase W₀ slightly decreased and thereafter increased with pH of the excess aqueous phase. In contrast, the resulting values of W₀ upon the back-extraction were independent of the excess aqueous phase pH for KCl, MgCl₂, and CaCl₂.