Abstract: In a process for the production of a soluble native protein, such as immunoglobulin or methionine-prochymosin, in which an insoluble form of the protein is produced by a host organism transformed with a vector including a gene coding for the protein, the insoluble form of the protein is reversibly denatured in an alkaline aqueous solution at a pH selected to promote dissociation of a group or groups of the protein involved in maintaining the conformation of the protein, and the protein is subsequently allowed to renature by reducing the pH of the solution below a pH effective to denature the protein to produce the soluble native form of the protein. The pH of the alkaline aqueous is suitably in the range 9.0 to 11.5.