Two series of poly(ester amide)s prepared from sebacic acid and different ratios of 1,12-dodecanediamine and a diamine that contains both alpha -amino acid residues and ester groups have been synthesized and characterized. In order to maintain hydrogen bonding interactions, two diamines with the same number of main chain atoms were selected. The series differ on the nature of the alpha -amino acid residue: glycine or L-alanine. The calorimetric analysis shows that melting temperatures increase as the amide/ester ratio does. Polymers derived from L-alanine show lower crystallinities and melting temperatures than those constituted by glycine units. Hydrolytic and enzymatic degradabilities of both series of poly(ester amide)s have also been studied. The ratio and nature of alpha -amino acid residues in the chemical repeat unit greatly affect the degradation rate.