In this article, an overview of the height geodetic data of Slovenia that were determined on a basis of observations from various tide gauges along the Adriatic coast is presented. This is followed by the definition of the Koper height geodetic datum as a part of a new height system of Slovenia. The height datum was determined on the basis of observations at Koper tide gauge, the rate of sea level change in Koper, and taking into account the local stability of the tide gauge.

Key words: tide gauge, sea level, sea level change, height datum