An investigation on AGE-peptides, originating by proteolysis of in vitro glycated proteins, was carried out by LC methods with different detection applied to the mixture produced by proteinase K digestion of in vitro glycated human serum albumin (HSA). Classical approaches, like spectroscopic (UV, fluorescence) and mass spectrometric methods (MALDI, LC/ESI/MS), show that the digestion mixture is highly complex. However, there are clearcut differences between the digestion mixtures of glycated and unglycated HSA, in the former case allowing identification of possible glycated peptides belonging to the AGE-peptide class. MS/ MS experiments on selected species seem to be promising as regards structural information.