It is possible to determine heights of selective locations through terrestrial means by tying these locations to the sea level. Practical heights in geodesy, known as orthometric heights are referred to the geoid, which is approximated by the mean sea level (MSL).
In the present study, A GPS and conventional leveling techniques were used to establish a network of (15) control points distributed inside Mosul University Campus, to be as a bench marks for the surveying applications which are very important and necessary for the civil engineering projects and the geophysical survey. The obtained results show that, there is an average variation between the orthometric heights measured by leveling instrument and the ellipsoidal heights measured by GPS, referred to as geoid undulation. ArcGIS9.1 software was applied in the study for the georeferencing process of the GPS measured dataset.

Keywords: GPS, orthometric height, mean sea level