In this paper we investigate fluctuations of the repetition period of geomagnetic Pc1 pearl pulsations. Starting from calculated repetition period we present a general formula for the deviation of the repetition period as a function of wave frequency and stochastic parameters of the medium along the ray trace. We then apply this formula for a dipole magnetic field with a simple plasma distribution, and show that a linear correlation between repetition period and its deviation is predicted. This correlation and the frequency dependence of fluctuations are then compared with experimental values measured from selected Pc1 pearl events observed in Finland. ¿ American Geophysical Union 1996