The paper presents local changes of plumb line direction in the area of Inowrocław, central Poland. The changes were determined by geodetic (GPS, leveling) and gravimetric surveys. The presented conclusions point out that increasing resolution of a precise quasigeoid model in areas with variable distribution of rock mass is necessary. The final results of the paper are suggestions concerning a practical approach applied to obtain proper values of plumb line deflections that can be useful for further detail research for making more precise local models of the quasigeoid., Zbigniew Szczerbowski, Piotr Banasik and Jacek Kudrys., and Obsahuje bibliografii