The proteolytic changes taking place in muscle proteins during the processing of dry-cured ham were evaluated from the point of view of its increased nutritional quality. Sodium dodecyl sulphate polyacrylamide gel electro-phoresis (SDS-PAGE) revealed the breakdown of several muscle proteins in dry-cured ham. Peptide analysis by both reverse-phase HPLC (RP-HPLC) or free solution capillary electrophoresis (FSCE) confirmed the intense proteolysis. Dry-cured ham also showed large amounts of all the free essential amino acids: valine (221.4 mg/100g muscle), methionine (90.8 mg/100g muscle), isoleucine (155.7 mg/100g muscle), leucine (246.9 mg/100g muscle), phenylalanine (37.0 mg/100g muscle), tryptophan (25.7 mg/100g muscle) and, in particular, lysine (509.0 mg/100g muscle). Thus, dry-cured ham constitutes a concentrated source of essential amino acids of great importance when the energy intake is low or in a poor nutritional quality diet.