In this study, we investigated the feasibility of injection molding (IM) and injection compression molding (ICM) for fabricating 3.5-in. light-guided plates (LGPs). The LGP was 0.4 mm thick with v-grooved microfeatures (10 mu m wide and 5 mu m deep). A mold was designed to fabricate LGPs by IM and ICM. Micromachining was used to make the mold insert. The Taguchi method and parametric analysis were applied to examine the effects of the process parameters on the molding quality. The following parameters were considered: barrel temperature, mold temperature, packing pressure, and packing time. Mold temperature in this investigation was in the conventional range. Increasing the barrel temperature and mold temperature generally improved the polymer melt fill in the cavities with microdimensions. The experimental results for the replication of microfeatures by IM and ICM are presented and compared. The height of the v-grooved microfeatures replicated by ICM was more accurate than those replicated by IM. Additionally, the flatness of the fabricated LGPs showed that ICM was better than IM for thin-walled molding. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1151-1159, 2011