The current state of performance of fiber-optic gyroscopes is discussed in relation to the needs of optical telescopes for tracking and setting. The principles of operation of fiber-optic gyroscopes are outlined, as well as their parameters and practical problems associated with telescope applications, such as fringe-shift measurements. Photon shot noise at the output, drift rate, and scale-factor stability are examined. Telescope configurations for an equatorial and alt-azimuth cases are discussed, along with such astronomical applications as tracking, slewing, static telescope, and field rotation. It is concluded that further improvements the fiber-optic gyroscopes will make an encoder scheme based on these devices competitive with conventionally encoded optical telescopes.