This paper deals with the application of Taguchi optimization technique to reduce warpage problem related to the shrinkage variation depended on process parameters during production of thin-shell plastic components for orthose part. For this purpose, a number of MoldFlow analyses are carried out by utilizing the combination of process parameters based on three-level of L-27 and L-9 Taguchi orthogonal design. The signal-to-noise (SIN) and the analysis of variance (ANOVA) are used to find the optimum levels and to indicate the impact of the process parameters on warpage and shrinkage. The results show that warpage and shrinkage are improved by about 2.17% and 0.7%. A verification test is also performed to prove the effectiveness of Taguchi technique after the optimum levels of process parameters are determined. It can be clearly inferred from this conclusion that Taguchi optimization is sufficient to solve the warpage problem with shrinkage for thin-shell plastic components of orthose part. (c) 2006 Elsevier Ltd. All rights reserved.