This paper presents the regional gravimetric survey of the central part of the Republic of Slovenia. The need for a new gravimetric survey, the survey plan and the actual field measurements are presented. Data processing, control calculations, data adjustment in the form of a gravimetric network and accuracy estimations of the results obtained during the regional gravimetric survey are described. Furthermore, the impact the new gravimetric data had on the quasigeoid model determined in 2016 and consequentially on determining normal height by GNSS levelling was analysed. The analysis were based on the comparison of the normal heights determined by GNSS levelling and the control points obtained from the 2010 and 2016 quasigeoid models. The results show that the new gravimetric data improved the newly calculated quasigeoid model or height reference surface of Slovenia and consequently made the determination of the normal heights by GNSS levelling more precise. The comparison of old and new height reference surfaces shows there are differences in investigated area from −6.9 cm to +9.0 cm and mean difference is 1.5 cm.