Ayman F.Elawady¹, Mohamed I.S.El Nasr ², Mohamed E. El Din Sanad², Amani Moussa³, Wessam M.Dehis^{4 1} Researcher Assistant, fixed and removable Prosthodontics Department, National Research Centre, Cairo Egypt ²Professor of Removable Prosthodontics Department, Faculty of Dental Medicine, Al- Azhar University- Boys, Egypt ³Associate Professor, Fixed & Removable Prosthodontics Department, National Research Centre, Cairo Egypt ⁴ Researcher, Fixed & Removable Prosthodontics Department, National Research Centre, Cairo Abstract: Objective: The purpose of this study was to assess Mechanical properties, color stability and biological potentials three acrylic resin denture base materials containing titanium oxide nanoparticles. Materials and methods: Two groups were designated: Group I (control): consists of self, heat and microwave cured acrylic resins and Group II (composite): were 3% of titanium oxide nano particles (TiO2 NPs) added to the same three acrylic resins. Specimens from both groups were fabricated to assess mechanical properties including: flexural, and impact strengths, and hardness in addition to color stability. Antifungal potential against Candida albicans was tested using agar disc diffusion and colony forming unit assays. Also, cytotoxic effects of control and composite resins were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Statistical analysis was performed using One Way analysis of Variance (ANOVA) and t -test, level of significance was set P<0.05. Results: composite group revealed higher mean values regarding the flexural, impact strengths and hardness than control group and it was statistically significant (P<0.05). Color changes mean values of control group were higher than composite and the differences were statistically significant (P<0.05). Furthermore, the composite demonstrate antifungal effect against C.albicans.  Although, no statistical significant difference (P>0.05) was detected between the two groups concerning the cytotoxic effects, chemically cured resin in both group recorded higher values Conclusions: addition of TiO₂NPs (3% wt.) to acrylic resins lead to improvement in their tested mechanical properties, enhancement of color stability and induced antifungal effect. Cytotoxic effects of composites were comparable to that of acrylic resins