To determine the effects of thermal accelerated aging on flexural strength and flexural modulus of conventional and CAD/CAM provisional crown and bridge restorative materials. Six provisional crown and bridge materials were selected for this study. Three conventional resins: Jet Set 4 (Lang), Luxatemp (DMG), and Protemp Plus (3M ESPE); and three CAD/CAM materials: ArtBloc Temp (Merz), Telio CAD-Temp (Ivoclar Vivadent), and Vita CAD-Temp (Vita). Specimens of conventional materials were fabricated using a custom-made aluminum mold 25 2 2 mm. CAD/CAM blocks were sectioned to the same dimensions. A total of 180 bar-shaped specimens were obtained (30 of each material) and were divided into three groups per treatment. Groups 1 and 2 were immersed in 37°C water for 24 hours, and 6 days, respectively. Group 3 was subjected to 5,000 thermal cycles between 5°C and 55°C in water with 35 seconds dwelling time. All specimens where tested for flexural properties using three-point bending protocol on an Instron 5566A at a crosshead speed of 0.5mm/min. The results were analyzed by one-way ANOVA and post hoc Tukey test with material type and aging conditions as the main variables. Significance level was set at (p<0.05).  Overall CAD/CAM materials demonstrated significantly higher flexural strength and flexural modulus over conventional resins. No significant difference in flexural strength and flexural modulus was found among three treatments except for: Luxatemp, which showed significant increased flexural strength and flexural modulus after thermal cycling, and Protemp Plus which showed increased flexural strength after 6 days of water storage.