We report significant performance improvement of a mode-locked fiber laser gyroscope. A Fabry-Perot cavity GaAlAs laser diode whose front facet was antireflection coated was used as a gain medium. The rms noise equivalent rotation rate measured with a time-interval counter was improved to 0.06 deg/root h. The long-term drift of the gyroscope signal was reduced to 100 deg/h after a polarizer was inserted into the laser cavity formed with a polarization-maintaining fiber. (C) 1997 Optical Society of America