In this project, N,N' -Bis [2-(methyl- 3-(4-hydroxyphenyl) propanoate)] isophthaldiamide, as a biodagradable monomer, containing chiral group was prepared by the reaction of s-tyrosine methyl ester with isophthaloyl dichloride. A series of novel optically active and biodegradable poly(ester-amide)s (PEA)s based on tyrosine amino acid were prepared by the solution polycondensation of new diol monomer with several aromatic diacid chlorides, were synthesized. For this purpose, optimized conditions in term of reaction time and temperature were studied and the influence of the time of reaction on the inherent viscosity and the yield of the PEA were examined. The resulting PEAs exhibited good yields, high thermal stability with inherent viscosities ranging between 0.25 and 0.42 dL/g and are soluble in polar aprotic solvents. The synthetic polymers were characterized by FT-IR, 1 H-NMR, specific rotation, elemental and thermogravimetric analysis (TGA) techniques and typical ones by 13 C-NMR, differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis. Because of the existence of amino acid in the monomer and polymer backbone, these materials are expected to be biodegradable; therefore, in the next part of the project, biological and biodegradability properties of synthetic diol and one of the polymers were investigated. Soil burial test of the diphenolic monomer and obtained polymer, and soil enzymatic assay showed that the synthesized diol and its polymer are biologically active and probably biodegradable in soil environment. Finally, to improve the dispersion and obtain the homogeneous distribution of ZnO nanoparticles in polymer matrix, the surface of nanoparticle was modified with two different silane coupling agent (?-methacryloxypropyltrimethoxy silane, KH570 and ?-aminopropyltriethoxyl silane, KH550) and was mixed with one of the prepared polymers which its biological properties were investigated. In this way, the organic chains of silane coupling agents can accomplish steric hindrance between inorganic nanoparticles and the process of agglomerate formation is extensively reduced and the hydrophobicity of the surface of nanosized ZnO is obviously enhanced. Novel poly(ester-amide)/ZnO bionanocomposites (PEA/ZnO BNCs) were prepared by embedding of different ZnO nanoparticle contents into polymer matrix via ultrasonic method as a facial and inexpensive route. The resulting bionanocomposites were characterized by FT-IR, XRD, TGA, DSC, FE-SEM, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The FE-SEM, AFM and TEM results indicated that the ZnO particles were dispersed homogenously in nano scale in PEA matrix. TGA and UV/vis confirmed that the thermal stability and optical properties of the polymer was improved.