A new class of active fiber devices based on piezoelectric coated optical fibers is currently being developed. The piezoelectric coating is used to produce acoustic waves within the optical fiber and these acoustic waves interfere with optical signals passing through the fiber waveguide. Optical phase modulation devices based on piezoelectric coated fibers have been demonstrated and the behavior of these devices will be reviewed. A second type of active optical fiber device has been fabricated by integrating a piezoelectric fiber coating with an intra-core Bragg grating, which acts as a reflection filter. The primary interest of this work is to produce a piezoelectric fiber optic tunable filter. These types of active all-fiber devices show promise for a variety of applications including telecommunications and sensing networks. The performance of active optical fiber devices that use piezoelectric coatings is dependent on the device structure and the piezoelectric properties of the fiber coating. Several important geometric parameters (e.g. coating thickness and device length) that influence device performance have been experimentally identified. Additionally, several relationships between the fiber coating sputter deposition process, microstructure, and properties have been observed for piezoelectric ZnO fiber coatings. Recent advances in the development of active all-fiber devices are presented.