The need for a minimally invasive method of single crown preparation is inevitable particularly with weakened tooth and those of high opportunity for pulp irritation. Therefore, strong, durable, and adapted restoration with less invasive finish line preparation is required. The purpose of this study was to evaluate the effect of finish line design and cement space thickness on the marginal accuracy and fracture resistance of monolithic zirconia crowns. Thirty crowns were fabricated from translucent zirconia (inCoris TZI) using Cerec in-Lab system, and divided into three main groups (10 each) according to the finish line type of the die (knife-edge, chamfer, and shoulder). Every group was divided into two subgroups (5 each) according to cement…show more content… The completed crowns were seated on the die and the marginal gap was evaluated. The cemented crowns were loaded until fracture by using universal testing machine. The collected data was statistically analyzed using three way ANOVA followed by Tukey’s post-hoc test and the significance level was set at P ≤ 0.05. Regarding the marginal gap; there was no statistical significant difference between different finish line designs or between different cement space thickness, but there was a statistical significant difference before and after cementation. Regarding the fracture resistance; there was no statistical significant difference between knife-edge and chamfer finish line designs, but shoulder group recorded the highest failure load values with statistically significant difference (P < 0.05). Neither finish line design nor cement space thickness has effect on the marginal gap of inCoris TZI crowns. Regarding the fracture resistance of TZI crowns; knife-edge margins can be used securely instead of chamfer one, and can be considered as a promising alternative to shoulder margin when minimally invasive preparation is