Introduction: Surface roughness of zirconia implants is an essential requirement for osseointegration. In order to avoid surface damage and phase transformation one strategy to generate a rough zirconia surface is sandblasting prior to sintering. The aim of the study was to investigate the effect of sandblasting before sintering on the flexural strength. Material & Methods: Ninty zirconia discs (Zenotec, Wieland) were investigated. Prior to sintering 30 samples were used in the as machined condition, 30 sandblasted with 120 µm and 250 µm Al2O3respectively (distance: 10 mm, 2 bar). Sintering was done according to manufacturer's instruction using the Vita Zyrcomat. The mechanical properties of the resulting sintered zirconia discs were analyzed by biaxial test with additional Weibull statistics according to ISO 6872. From 10 discs of each group Ra values were measured before and after sintering process (surface topography with 121 profiles over an area of 3x3 mm; Perthometer S6P, Mahr, Göttingen). Results: The biaxial flexural strength depending on the sandblasted particle size was 584 ± 81 MPa for 120 µm, 476 ± 61 MPa for 250 µm and 1298 ± 267 MPa for the machined control group. The Ra values before and after sintering were 3.17 ± 0.39 and 2.95 ± 0.06 µm for 120 µm, 4.01 ± 0.15 and 3.86 ± 0.11 µm for 250 µm sandblasted samples, 0.31 ± 0.1 and 0.27 ± 0.08 µm for the as machined samples. Conclusion: Similar to sandblasting after sintering sandblasting prior to sintering revealed decreasedbiaxial flexural strength to 45% (120 µm) and 37% (250 µm). Acknowledgement: This study was supported by Wieland Dental &Technik, Pforzheim. Keywords: zirconia, biaxial flexural strength, sandblasting, surface roughness