Selective separation of concanavalin A (Con A) using alkylglucoside (AGn) as an affinity Ligand was achieved by two different methods in reverse micellar systems. The first method used the sodium bis(2-ethylhexyl)sulfosuccinate(AOT)/butanol/iso-octane system, in which Con A was extracted effectively when AGn was added to the system but was not extracted at all without AGn. Selective extraction was attained in three steps. In the first step, reverse micelles composed of AOT and alcohol without AGn were used. Proteins extractable to these reverse micelles were removed from the aqueous phase. In the second extraction step, Con A was selectively extracted to the reverse micellar phase with AGn. Backward extraction was successfully performed using buffer solutions containing glucose. The problem of this method was the precipitation of Con A at the liquid/liquid interface presumably due to the denaturation of Con A by AOT. The second method used the reverse micellar system composed of tetra-oxyethylenedecylether. This reverse micellar system had no ability to extract water-soluble proteins without an affinity ligand, whereas Con A could be extracted selectively with high overall efficiency when AGn was added to the system. Rapid backward extraction was performed using a buffer solution containing glucose or methyl-cr-glucoside by adding ethanol or butanol.