Injection molding is a complex process for many production engineers as it involves selection of many process parameters to produce quality products to meet customer requirements. Determination of the optimal process parameters in injection moulding is an important design task as it influences part quality, production rate, and production cost and energy consumption. The purpose of this paper is to investigate the effect of selected process parameters in injection moulding on part quality. The paper applies Taguchi's parametric design and analysis of variance (ANOVA) technique to study the effect of process settings of plastic injection molding on part quality. Experimental data are used to identify the relationship between the injection molding process parameters and product quality. Mold surface temperature, melt temperature, mold open time and ejection temperature are selected as the process control parameters. Warpage and sink mark depth are selected as the multi-product quality characteristics.