present study investigated the mechanical properties (flexural strength) with different concentrations of Zirconia-Impregnated PMMA Nanocomposites. Method: In present systematic review and meta-analysis, all articles published until the end of July 2023 through searching in databases PubMed, Scopus, Science Direct, ISI, Web of Knowledge, Elsevier, Wiley, and Embase and Google Scholar search engine were extracted using keywords and their combinations by two trained researchers independently. Data analysis was done using the fixed effects model in meta-analysis, by STATA (version 17); P-value less than 0.05 was considered significant. Result: A total of five studies were included in the meta-analysis process. mean differences of flexural strength between 1.5% nano-ZrO2 and control group was 17.14 MPa (MD:17.14 95% CI; 15.83 to 18.45; p<0.001). There was no statistically significant difference (p>0.05) between the flexural strength of the specimens reinforced with 7% nano-ZrO2 nanoparticles groups and those in control group (MD: -0.42 MPa 95%CI; -4.77 to 3.93; p=0.85) (Fig.5). Conclusion: The optimal filler concentrations for reinforcing PMMA denture base resins from the flexural strength perspective were 1.5%, 3 and 5 wt.% ZrO2.