At the beginning of sixties i.e. seventies the only two, until now, Republic of Serbia territory geoid determinations were published. Undulations were determined according to adopted reference ellipsoid of Bessel and determinations themselves were based on astronomical data (astrogeodetic leveling). Unfortunately, solutions do not correspond to today's scientific and technical needs due to their accuracy and their resolution. Therefore, there have been done series of undulation determinations that relate to ellipsoid WGS84, by different methods, but only in two localities within the area of 50 x 50 km. Determinations themselves are treated as determining tests, aiming at analyzing existing material that is available. In this paper-work only determinations of local geoid are shown using collocation on basis of regional gravimetric measurements of Republic of Serbia.