One of the most interesting and challenging tasks in several fields and applications of geodetic surveying is obtaining orthometric or geoid heights. Determination of orthometric heights using traditional methods such as levelling works with different orders and standards is difficult and hard due to its long time, high cost, and big efforts but it is considered as the most accurate technique in determining orthometric heights. With the wide spread development of Global Positioning System and its different techniques and applications in the last periods, It was important to study the ability of using some of its applications instead of levelling works, and to investigate the accuracy obtained from each one of these techniques. So the objective of this research is to study the use of several modern GPS satellite techniques and applications , such as local and global geoid models and precise point positioning, for determining orthometric heights, and also to evaluate the effect of using these techniques by comparing their results with that obtained from surveying levelling. The study area is located in Egypt and divided into two separated zones along the Mediterranean and Red Sea coastal lines. These areas are particularly important in order to assess the impacts of climate change and global warming using different suitable defense strategies. It has been found that local geoid model technique gives the best results comparing with the other techniques. It is recommended that a precise local geoid for all Egypt zone area should be created by co-operation of all interested organizations in this field.