A method of calibrating bias drift with operating temperature over an operating temperature range for a vibrating structure gyroscope. The method includes the steps of measuring, over an operating temperature range of the vibrating structure gyroscope, primary drive means voltage P, vibrating structure frequency f, secondary drive quadrature component values S.sub.q which is a measure of real component bias errors with temperature, and secondary drive real component values S.sub.r which is a measure of change in bias, that is the zero inertial rate offset, of the vibrating structure gyroscope with temperature, substituting the values obtained in the relationship.times..times..times..times..times..times. ##EQU00001## where a.sub.klm are bias calibration coefficients for the vibrating structure gyroscope over the operating temperature range, and calculating from the relationship the coefficients a.sub.klm to provide a set of bias calibration coefficients for the vibrating structure gyroscope over the tested operating temperature range.