Ahmed Attia Abo El-Naga¹, Abeer Abd-Elsallam El-fallal², Shaimaa Ahmed Abo El-Farag Ibraheim³, Hosam Alegaly Alaraby^{4 1} Professor of Fixed Prosthodontics, Faculty of Dentistry, Mansoura University,Egypt. ² Associated Prof. of Dental Biomaterials, Faculty of Dentistry, Mansoura University, Egypt. ³Lecturer of Fixed Prosthodontics, Faculty ofDentistry, Mansoura University, Egypt. ⁴ B.D.S, Tripoli, Libya. Abstract: Objectives: The purpose of this in-vitro study is to investigate the effect of intaglio surface conditioning on the fracture strength of veneered Zirconia crowns compared to full-contour Zirconia crowns. Methods: Thirty two human maxillary premolars were prepared for two Zirconia all-ceramic crown Systems with the following preparation criteria: 6-degree axial taper, 1-mm shoulder finish line, 2-mm occlusal reduction and occluso-gingival height of 5 mm. All specimens were divided in to two groups (N=16) for each ceramic material. In the first group all prepared premolars restored by full contour zirconia crowns (MAD/MAM) while in second group all teeth restored by veneered zirconia crowns. The cores directly fabricated (VITA In-Ceram blocks) by (MAD/MAM) and build-up by ceramic. Each group subdivided into two subgroups (N=8). Crowns of first subgroup sandblasted with 50μm Al2O3while the second subgroups not treated by sandblast.All specimens were loaded in a universal testing machine with the compressive load (N) applied along axis of the specimen. Fracture load was recorded for each specimen. The kruskal-wallis test was used first and followed by Mann-whitney tests. Results: The fracture resistance records high significance difference between VZ and FZ (P=0 for both tests) irrespective to the type of surface treatment. Contrary, both tests proved that the surface treatment has no significance effect on fracture resistance irrespective to the type of material (P=0.72 for Median test and P=0.27 for Mann-Whitney test). Conclusions: Full-contour zirconia showed higher fracture resistance than veneered zirconia crowns. Surface treatment (sandblasting) has effect on fracture strength mean, but no significance difference statistically. Keywords:Fracture Strength, zirconia all-ceramic crown, intaglio surface conditioning..