Abstract: PMMA/CaCO3 nanocomposites have been fabricated by in-situ polymerization. The influence of concentration and stirring speed on tensile strength have been studied. The experimental results were optimized using Taguchi’s approach. L9 Orthogonal arrays of Taguchi, the signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) are employed to find the optimal input parameter levels and to analyze the effect of these parameters on tensile strength. Experimental results showed that tensile strength PMMA/CaCO3 nanocomposites increased up to 53 % at 0.6 wt. % CaCO3 and 1000 rpm in comparison to corresponding pure PMMA. The experimental results and various statistical approaches namely, Taguchi methods, Conceptual S/N ratio and drew similar conclusions. The ANOVA analysis showed that speed is more dominant in comparison to concentration.