Purpose: This in vitro study evaluate a new CAD/CAM provisional prosthetic material in comparison with two commonly used provisional prosthetic materials regarding the marginal accuracy at different water storage conditions. Materials and methods: Three different provisional materials (VITA CAD-Temp, Protemp 4 and Acrostone) were used to fabricate 15 temporary bridges on two prepared teeth (stainless steel dies were milled with 5 mmoccluso-gingival height, 9 mm external cervical diameter, 7 mm internal cervical diameter, 5 mmocclusal diameter, 10 degrees occlusal convergence angle and 1 mm thickness shoulder finish line), and examined for marginal accuracy using stereomicroscope before and after 2 different conditions of water storage (one day, two weeks). Results: ANOVA test showed (P- value < 0.001) there was no statistically significant difference between VITA CAD-Temp after two weeks and Acrostone pre-cementation; (0.027±0.005, 0.022±0.006 mm respectively); both showed the statistically significantly lowest mean gap distance. Conclusion: Water storage significantly affects the vertical marginal gap distance of the tested provisional restorations. VITA CAD-Temp showed decreased vertical marginal gap after two weeks water storage after cementation compared to pre-cementation values.