Polyhydroxyalkanoates (PHA) are storage macromolecules of the cell synthesized by prokaryotic organisms under specific conditions of unbalanced growth, when the synthesis of the major compounds is reduced, but there is excess carbon in the medium. PHAs have many attractive properties that make them promising materials for various applications, including biomedical ones. PHAs are very promising polymers as, being thermoplastic, like polypropylene and polyethylene, they have antioxidant and optical properties as well as piezoelectricity. PHA properties vary depending on the structure of the side groups in the polymer chain and the distance between ester groups in a molecule. Many companies have been engaged in the commercialization of PHA production technologies. PHAs are used to manufacture agricultural devices. These are films for greenhouses, packages for fertilizers and vegetables, pots, nets and ropes. Physical and mechanical properties of PHAs are determined by the molar percentages of monomers in the polymer. The properties of homopolymer PHAs are significantly different from those of copolymer PHAs.