Magnesium alloys have been considered to overcome most of these difficulties [8; 9; 10; 11; 12; 13; 14; 15; 16]. However, not all of them could be considered as proper materials for resorbable medical implants, especially those containing high concentrations of elements such as zirconium, aluminum, and rare earth metals that may induce inflammatory cascades and tissue damage [5; 17; 18; 19; 20; 21]. The magnesium alloy AZ31, which is characterized by a relatively low content of aluminum (3%) and zinc (1%), has been experimentally proved to possess good biocompatibility [11; 12]. Due to its good balance among mechanical, biocompatibility, and biodegradation characteristics, Mg AZ31 alloy may be a suitable bioresorbable implant material. However, it should be considered that because several clinical treatments, such as bone healing, may require up to 12 weeks to complete [5], material with more reliable and controlled corrosion kinetics should be adopted to prevent bioresorption from occurring before tissue healing is accomplished. Uncontrolled or high corrosion rates in the physiological environment may result in the bioresorbable implant's early embrittlement and loss of structural integrity [14]. Technological solutions that enable reduction and control of degradation rates can favor a wider utilization of biodegradable temporary implants, avoiding concerns about metal fix implants [21; 22]. Different approaches, such as alloy composition, surface modification, and conversion coatings, have been proposed to improve and to better control the corrosion kinetics of magnesium alloys [14; 22; 23; 24; 25; 26]. Namely, ion implantation [27; 28; 29], organic coatings [30; 31; 32; 33], alkali heat treatment, micro-arc oxidation [34; 35; 36], and polymer coating [37; 38; 39] have been proposed. Among these, biodegradable polymer coatings have been described to have better performance [40; 41; 42], even if not yet providing proper coating durability or good biocompatibility. PHB (Poly-\(\beta\)-hydroxytrate) is a natural macromolecule polymer secreted by microorganisms under the condition of unbalanced growth that was chosen for our study as a biodegradable protecting and corrosion rate-controlling coating for magnesium alloy [32]. PHB and its copolymers are already used in a wide range of applications for drug release and tissue engineering, since it is naturally and not toxically biodegradable in CO\({}_{2}\) and H\({}_{2}\)O by the human metabolism and does not cause body immune exclusion. Tissue response to PHB degradation byproducts is debated. Rat subcutaneous tissue reactions following implantation of PHB and PHB/VA have been reported [43] with the hypothesis that mononuclear giant cells infiltrate hyperplasia of fibroblasts, and mature fibrous capsules were a typical reaction associated with an increase in the collagen deposition induced by PHB degradation byproducts. However, in vivo tests run [44] using PHB films implanted subcutaneously in rabbits' legs for 8 weeks showed that the presence of macrophages was not accompanied by any acute inflammation or abscess formation. The experiment suggested that PHB material has good biocompatibility and biodegradation [45] associated to good chemical and mechanical properties for biomedical applications [15; 46; 47; 48; 49; 50; 51; 52; 53]. In the present work, both the surface characterization and biological response of magnesium alloy AZ31 coated with poly-\(\beta\)-hydroxybutyrate (PHB) were evaluated to investigate whether it could induce low hemolysis and its effects on cell viability. Such experimental research provides a preliminary evaluation of magnesium alloys with PHB coating as vascular stents and hard tissue repair materials, and it will serve as a base and reference for their future potential clinical applications.