The use of an optical fiber gyroscope in automotive navigation is reported. The performance requirements for a navigational gyroscope are discussed in terms of the input range, resolution, and bias and scale errors. The OFG-3, an automotive optical fiber gyroscope prototype, is introduced, and its error sources are related to the gyroscope designs. The gyroscope is made of polarization maintaining fibers and incorporates optical phase modulation and synchronous demodulation techniques. The gyroscope electronics restrict the resolution and the bias error, while the optics dominate the scale error. The microcomputer in the electronics compensate for the scale error, and the OFG-3 meets navigational requirements, Automotive navigation has been demonstrated using the gyroscope in combination with a map-matching algorithm.