Аннотация:Long term UBV photometric observations of the well-known X-ray binary system HZ Her/Her X-1 were analyzed. It was found that the orbital light curve is stable for the entire 16-year period of observations. It is conjectured that the small observed deviations from the average orbital light curve are associated with geometric effects and can be explained on the basis of the model of a precessing twisted accretion disk.