Objective: The aim of this in-vitro study was to evaluate the flexural strength of CAD/CAM interim material compared to two currently used resin based interim materials after thermocycling.Material and methods: A total of thirty bar shaped specimens were constructed with standardized dimensions (25mm length x2mm height x2mm width) following the ADA specification # 27 for flexural strength testing. Specimens were divided into three groups of 10 samples each according to the material tested:*Group I (n=10); Machinable CAD/CAM resin blocks. (CAD-temp)*Group II (n=10); Dual-cured resin based material. (Temp-Span)*Group III (n=10); Self-cured resin based material. (Protemp 4)Each group was subdivided into two equal subgroups of five samples each according to aging condition. Subgroup (A),control Subgroup (B): strorage were performed for fourteen dats in an artificial saliva solution then thermocycled for 2500 cycle at temperature ranging from 55, 37, 5 0C , the dwell time was 6 seconds in each water bath.All samples were placed on a universal testing machine for three-point-bending test with a crosshead speed of 0.75 mm/min. Results: Protemp without aging showed the highest mean flexural strength value (100.24 ± 6.2) followed by Protemp with aging (85.912 ± 4.8).Tempspan without aging showed statistically significantly lower mean flexural strength value (69.51 ± 5 Mpa) followed by Tempspan with aging (64.930 ± 1.6).There was no statistically significant difference between CAD Temp without aging (39.42 ± 4 Mpa) and CAD Temp with aging (37.712 ± 1.2Mpa); both showed the statistically significantly lowest mean flexural strength values.Conclusion: ProTemp4 exhibit higher mean flexural strength value than TempSpan followed by CAD-Temp that exhibit the least mean values. Artificial aging (storage and thermocycling) has direct relationship to the reduction of flexural strength values, but has no significant effect on the mean flexural strength values of the CAD-Temp interim restorative material. Composite based materials seem to offer clear advantage regarding flexural strength, therefore, be considered materials for future manufactured interim restorations.