Rotational molding of thermoplastics has become an important process in industry. However, the optimization of this technique has been essentially based on a trial-and-error process. In this report, an L＇16 experimental matrix design based on the Taguchi method was conducted to optimize the impact strength of rotationally molded parts. Oven temperature and oven time were found to be the principal factors affecting the impact property of rotationally molded thermoplastics. Density and melt flow index measurements were also employed to identify the material and structural parameters. The part density increased with increasing total energy transmitted into the molding system. The melt flow index provides an easy indication of the mechanical properties of rotationally molded parts.