Space geodesy techniques can determine baseline lengths upto 1000km with accuracy better than 10-8. However, mismodeling ofthe tropospheric delay experienced through the electrically neutralatmosphere is a serious error source. This propagation delay can bedivided into two parts according to their origins. The first ishydrostatic (dry) and the second is the wet delay. Both the dry and wetdelay can be described as a product of the delay at the zenith and amapping functionDry delay is in the range of 2.2-2.4 meters at the zenith andconstitutes about 90% of the total tropospheric delay. The currentpaper studies the temporal and spatial variation of the dry delay in theEgyptian territory. To study this phenomenon, ray tracing based onMSIS dry model is used at nine well distributed sites over Egypt forone year. It was found that Aswan shows the minimum value of zenithdry delay with a value of 2.24 meters. The zenith dry delay variesthrough the year, such that it assumes its minimum value duringspring and autumn months, especially April and May. The maximumvalue of the zenith dry delay happens during summer months,especially June and July. Keywords: Tropospheric delay, temporal variation, spatial variation