Poly(beta -hgdroxybutyrate) (PHB) is st bacteria storage biodegradable polyester that is considered to be a natural substitute for synthetic thermoplastics in many applications. However, brittleness hampers its utility. This study shows that oriented elastic fibers of PHB with favorable mechanical properties (360-MPa tensile strength and 5.6-GPa Young's modulus) can be produced by the spinning and drawing of a concentrated PHB gel using a three-stage fiber processing technique.