Objective: The aim of this study was to investigate the effect of immersion time in artificial salive on the flexural strength of provisional crown and bridge (p-c&b) materials. Materials and Methods: Two types of p-c&b materials were used in this study: Light polymerized p-c&b material (Revotek LC) and autopolymerized p-c&b material (PerfecTemp II). A total of 100 specimens were fabricated and measured according to ISO 4049/2000. A stainless steel mould was used to prepare 2mmx2mmx25mm bar shaped specimens. All materials were dispensed and manipulated according to the manufacturers' instructions. The specimens were divided into 5 groups (n=10). Each specimen of the first group was measured immediately after preparation. The second, third, fourth and fifth groups were immersed in artificial saliva at 37ºC in an incubator for 1 hour, 1 day, 7 days, and 14 days, respectively. Flexural strength was tested by Universal Mechanical Testing Machine Shimadzu in a 3-point bending test. The repeated ANOVA and Post-Hoc Bonferroni test were used to compare the continuous variables between the groups. Results: The results showed flexural strength of Revotek LC were higher than PerfecTemp II at first and second group. However, flexural strength of PerfecTemp II was higher than Revotek LC at third, fourth, and fifth group. The highest flexural strength of Revotek LC was achieved in 1 hour immersion, whereas PerfecTemp II achieved the highest value in 7 days. Conclusion: Flexural strength of p-c&b materials were influenced by immersion time in artifical saliva and the type of p-c&b materials.