The availability of recombinant cytochrome c peroxidase from yeast has already proved to be of considerable importance in developing the protein engineering of peroxidases and of metalloproteins in general. With the recent increase in information on peroxidase sequences, further developments in recombinant expression systems and the determination of an increasing number of peroxidase crystal structures, it should soon be possible to make significant advances in engineering peroxidases for biotechnological purposes.