The present work describes the high-performance liquid chromatographic (HPLC) separation of water-soluble peptides of eight quarters of raw milk Swiss Emmental cheese leaves which were packaged at 3 months in plastic wrap. The leaves were manufactured with (n = 4) and without (n = 4) the addition of L. Casei subsp. Casei to the usual starter culture. Samples were analysed at 3, 6, 9 and 12 months of ripening. The water-soluble peptides were separated by HPLC and analysed using a UV-detector at 210 nm. More than 100 peaks could be resolved. Analysis of variance and principal component analysis of the peak heights led to the following conclusion: 15 peaks increased and seven peaks decreased during the ripening period from 3-12 months. Cheese produced with L. Casei subsp. Casei showed three larger and two smaller peaks than those produced without this adjunct. The corresponding peptide composition was not determined