Reggianito argentino is a hard cooked cheese, which is normally produced with natural 'wild' whey cultures. In the present work, we compared proteolysis during the ripening of cheeses made with natural whey cultures and defined multiple- or single-strain cultures of Lactobacillus helveticus (SF133, 138 and 209). For that purpose, we performed RP-HPLC of ethanol (70%)-soluble and -insoluble fractions of the cheese and analysed levels of free amino acids. Principal component and non-hierarchical cluster analyses were applied to chromatographic and free amino acid data and samples were classified into three clusters with increasing proteolysis. Cheese produced with strains of L. helveticus 133-138 was grouped in the cluster with lowest proteolysis, while cheese manufactured with strains 209-138 was in the group with highest proteolysis. The remainder of the cheeses were grouped in the intermediate cluster or in the group with highest proteolysis, depending on the index of proteolysis studied. Control cheese and cheese made with the three-strain starter (133-138-209) were always grouped in the same cluster, which indicates that reggianito argentino can be produced with this defined starter culture without changes to its patterns of proteolysis.