Currently, there is a large growth in the use of thermoplastic composites reinforced with long glass fiber. These composites have the mechanical properties required for structural and automotive applications since they present a high mechanical strength and a low specific weight. However, the injection molding processing affects both the mechanical strength and visual appearance. The mechanical strength is related with the residual length of the fibers in the composite and its orientation. The surface quality depends on the formation of a thin polymer layer on the outside of the composite avoiding the outcropping of the fibers to its surface. In this study, a long glass-fiber reinforced polyamide 6.6 with 50 wt% was processed by injection into a mold specifically designed for this material. A design of experiments (DOE) was used to evaluate the influence of processing parameters on the two response variables: flexural strength and surface quality. A factorial experiment with three factors (barrel temperature, volume flow rate and screw rotation speed) at two levels (high and low) was used, totaling eight treatments. The other injection parameters were kept constant. The aim of this study was to determine the processing condition that maximizes both the flexural strength and visual quality of the molded composite. It was found that the parameters influencing the flexural strength are the barrel temperature and screw rotation speed, which should be maintained at the highest levels to maximize this property. The volume flow rate did not affect this feature within the studied levels. The response variable surface quality is affected by the barrel temperature and volume flow rate. These two parameters must also be kept at high levels to maximize this response variable. The screw speed did not affect this variable. In order to maximize both flexural resistance and surface quality, all the studied injection parameters must be kept at higher levels.