The invention relates to a method for producing recombinant RNase A in E. coli. Said method is characterised in that it uses a DNA sequence, which codes for an RNase A of bovine origin and which is adapted to the codon usage in E. coli. The invention relates to nucleic acid molecules, which contain a nucleic acid sequence that has been adapted to the codon usage in E. coli and to recombinant nucleic acid molecules, which contain an nucleic acid molecule of this type and permit the expression of the recombinant RNase A in E. coli.