β-Hairpin peptidomimetics of the general formula cyclo(-Xaa1-Xaa2-Thr3-Xaa4-Ser5-Xaa6-Xaa7-Xaa8-Xaa9-Xaa10-Xaa11-Xaa12-Xaa13-) and pharmaceutically acceptable salts thereof, with Xaa1, Xaa2, Xaa4, Xaa6, Xaa7, Xaa8, Xaa9, Xaa10, Xaa11, Xaa12 and Xaa13 being amino acid residues of certain types which are defined in the description and the claims, have elastase inhibitory properties, especially against human neutrophil elastase, and can be used for preventing infections or diseases related to such infections in healthy individuals or for slowing infections in infected patients. The compounds of the invention can further be used where cancer, or immunological diseases, or pulmonary diseases, or cardiovascular diseases, or neurodegenerative diseases, or inflammation, or diseases related to inflammation, are mediated or resulting from elastase activity. These peptidomimetics can be manufactured by a process which is based on a mixed solid- and solution phase synthetic strategy.