The trend of development of gyroscopes used in Inertial Navigation and Guidance systems, led to the adaptation of vibrating gyros to fulfil the basic requirements on such systems specially for military applications in aircraft and guided missiles. The oscillogyro is a new type of vibrating gyroscopes suitable for stabilizing inertial platforms. It is characterized by its simplicity, reliability and low cost of production. In this work, the application of oscillogyro in inertial navigation systems (INS) is introduced. After a short description of the oscillogyro as a two axes rate or displacement gyro, the mass- unbalance error is analyzed. The propagation of such error into an INS with single-axis vertical indicating platform, is investigated. The results of analysis show quite satisfactory performance and promising future for the application of oscillogyro in a wide range of INS and guidance systems.