The high crystallinity, low solubility in normal solvents, and low hydrophilicity of poly(p-dioxanone) (PPDO) are unsuitable for the expansion of its biomedical applications. In order to circumvent these problems and induce biological properties, a series of poly(ester amide)s based on p-(dioxanone) and l-phenylalanine were synthesized by copolymerization of p-dioxanone with l-phenylalanine N-carboxyanhydride monomers. The structures of the copolymers were confirmed by H-1 NMR. The crystallinity of the copolymers was investigated by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Increasing contents of phenylalanine resulted in decreased crystallinity owing to the rigid phenyl groups of phenylalanine, which disrupted the regularities of the chains, thus confining their movement. The synthesized copolymers were more soluble in chloroform than PPDO. Moreover, the copolymers were more hydrophilic and hydrolyzed more slowly than PPDO, as indicated by water angle contact measurements and in vitro hydrolysis studies. Especially, the copolymers showed inhibition on cell proliferation of L929 mouse fibroblasts by MTT assay, suggesting that the polymers might be useful in the areas where cell proliferation need to be inhabited such as adhesion prevention. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2311-2319, 2013