Cavity balancing is the process of altering the flow front within a cavity through thickness and design changes such that the desired fill pattern is achieved. The 2 dimensional (2D) cavity-balancing algorithm, developed by Lam and Seow [1] can only handle 2D geometry. This represents a major drawback as most, if not all of the practical injected parts are not 2D parts. To overcome this difficulty, the present investigation has developed a 2.5 dimensional (2.5D) cavity balancing optimization routine implemented within a 2.5 D finite elements domain. The aim of the automated cavity balancing routine is to reduce product development time and to improve product quality. This will lower the level of prerequisite expert knowledge necessary for successful mold and part design. The automated cavity balancing routine has been developed using the concept of flow paths. The hill-climbing algorithm of Lam and Seow is utilized but modified for the generation of flow paths for 2.5D parts. The algorithm has been implemented in a computer program running as an external loop to the MOLDFLOW software. Case studies are provided to demonstrate the efficiency of this routine. / Singapore-MIT Alliance (SMA)