A novel protein refolding technique utilizing reversed micelles has been developed. Denatured RNase A solubilized in the reversed micellar solution was reactivated by addition of glutathione entrapped in another reversed micellar solution. This novel refolding method facilitates a high renaturation yield at high protein concentration compared to achievable results in dilution method. Novel refolding technique by reversed micelles makes it possible to activate proteins from insoluble aggregates by direct dissolution into the reversed micellar solutions.