Thermal analysis of a series of dipeptides having alpha-alanine as the first term was carried out by simultaneous TG-DSC measurements. The thermal behaviour of these compounds was compared to that of the independent free alpha-amino acids contained in the dipeptides. The reciprocal influence of the two alpha-amino acids makes the dipeptides less stable than the single components. The TG-DSC curves provide a rapid recognition of the presence of the compounds which retain the respective decomposition peaks of the independent free alpha-amino acids.