Web gate system of aluminum castings in permanent molds is investigated in order to improve the quality of aluminum castings produced in permanent molds. The metal flow in the mold were observed and conducted using graphite molds and real time X-ray radiography recorded at a rate of 30 images per second through those molds. The affects of web thickness on flow patterns, gas entrapment, jetting possibility are studied and discussed. Flow and solidification simulation programs were employed to predict the flow behavior under the different conditions that can prevail in permanent mold gating. The study highlights the characteristic features of web gate system used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects, and provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.