The Global Positioning System (GPS) is rapidly becoming an important tool to the surveying and mapping applications. GPS is revolutionizing the surveying profession by providing fast, cost-effective positioning. One primary task in combining GPS data with terrestrial data is the transformation of geocentric WGS84 coordinates to local terrestrial coordinates. Different local ellipsoids are primarily used because certain sized ellipsoids fit a particular portion of the earth better than a global ellipsoid. To achieve the referencing of a local datum to WGS84, one major requirement is to have well distributed geodetic control points common to both systems. In Egypt, the transformation parameters between the local reference ellipsoid (Egyptian Geodetic Datum EGD, Helmert 1906) and WGS84, all over the country can be found, through using special mathematical models. The situation in Egypt is not very well, the transformation parameters are not accurately defined till now, because of the lack and bad distribution of the available data. The main objective of the current study is the determination of new sets of the transformation parameters, zonal approach, over the Egyptian territory for combining GPS data and terrestrial data in Egypt in accurate form as possible.