Baltic States have changed their national height systems from Baltic Normal Height System 1977 (BHS-1977) to European Vertical Reference System (EVRS) realizations. There is a transformation formula for getting height difference theoretical value between EVRS realizations and BHS-1977. Performing practical Global Navigation Satellite System (GNSS) measurements and obtained data mathematical processing, there is a possibility to calculate point height difference between GNSS data and data of 1st order levelling networks. For GNSS measurements use for height determination it is very significantly to use advanced measuring technologies and verified data processing methodology. Performed measurements have high accuracy which describes RMS errors. Average error value for axis N and E is 0.001 m, but measurement height component average error value is 0.003 m. Correct and reliable height reference system is an important part of economic planning in Baltic region while the world ocean level rises and rapid climate changes happens.