Abstract: The invention relates to a process for recombinant preparation of peptides by expression of a DNA in micro-organisms, which DNA codes for a fusion protein made of streptavidin and one of the said peptides. Streptavidin and the peptide are bound by a peptide sequence which can be cleaved by an endoproteinase. The process also includes isolation of the insoluble, inactive protein, solublisation of the inactive protein using a denaturant, dilution of the denaturant at a pH value of between 8.5 and 11 until cleaving of the fusion protein by an endoproteinase can take place, cleaving of the fusion protein, lowering of the pH value until streptavin and non-cleaved fusion protein precipitate, and cleaning of the desired peptide from the supernatant. Said process is particularly suitably for producing parathromone and urodilatin and fragments thereof.