Fully reduced hen egg-white lysozyme was refolded by a dilution method using a flow-type reactor. The refolding efficiencies in the flow-type reactor were almost the same as those in a batch system. In the flow-type reactor the denatured lysozyme was continuously diluted in a small mixing unit and lead to a packed column with nearly plug flow. The unfavourable effects of mixing time on protein refolding, which becomes significant in a lar ge scale operation, can be avoided in this system. A variety, of operations, such as changing temperature and addition of other reagents, can be applied at specific stages of the refolding process. Protein refolding with the flow-type reactor has flexibility to meet various requirements for efficient protein refolding.