In this project, a series of novel thermally stable polyamides (PA)s, polyesters (PE)s, and poly(ester-imide)s (PEI)s based on biodegradable amino acids moieties such as L-methionine, and L-leucine were synthesized. Some physical properties of them were investigated. First, in order to prepare new aliphatic-aromatic PEIs based on N -trimellitylimido-L-methionine as a monomer, direct polycondensation reactions of this monomer with various bisphenols took place in the presence of thionyl chloride/pyridine (Py) as condensing agent. Favorable conditions in terms of reaction time, and temperature were also investigated. The resulting PEIs were obtained in good yields and exhibited low to moderate inherent viscosities ranging from 0.15 to 0.40 dL/g. Also, an attempt was made to construct the new monomer with chiral architecture containing of bulky aromatic diacid by using L-leucine, phthalic anhydride, and 5-aminoisophthalic acid, 5-(4-methyl-2-phthalimidylpentanoylamino)isophthalic acid was synthesized in three steps. This monomer could react with aromatic diols via direct polycondensation by using tosyl chloride/ N,N' -dimethyl formamide/Py as condensing agent in order to prepare thermally stable optically active PEs in high yields and inherent viscosities in the range of 0.23-0.52 dL/g. Also a new process of polycondensation of this monomer with different diamines for producing extended PAs was carried out either in the presence of N -methyl pyrrolidone/triphenyl phosphate (TPP)/calcium chloride/Py as condensing agent, and TPP with ionic liquid both as solvent, and catalyst as the other condensing agent. Inherent viscosities of these polymers were in the range of 0.27-0.41 dL/g, and 0.38-0.55 dL/g respectively, and it exhibited good solubility and thermal stability. It seemed that in the presence of ionic liquids, better results were obtained. The chemical structure of monomers, and polymers were confirmed by elemental analysis, FT-IR, 1 H-NMR, and 13 C-NMR spectroscopy, elemental analysis, and specific rotation.