Objective: To compare in vitro the marginal adaptation of crowns manufactured using ceramic restoration fabricating techniques. Method and Materials: Fifty standardized master steel dies simulating molars were produced and divided into five groups, each containing 10 specimens. Test specimens were fabricated with CAD/CAM, heat-press, glass-infiltration, and conventional lost-wax techniques according to manufacturer instructions. Marginal adaptation of the test specimens was measured vertically before and after cementation using SEM. Data were statistically analyzed by one-way ANOVA with Tukey HSD tests (α = .05). Results: Marginal adaptation of ceramic crowns was affected by fabrication technique and cementation process (P .001). The lowest marginal opening values were obtained with Cerec-3 crowns before and after cementation (P .001). The highest marginal discrepancy values were obtained with PFM crowns before and after cementation. Conclusion: Marginal adaptation values obtained in the compared systems were within clinically acceptable limits. Cementation causes a significant increase in the vertical marginal discrepancies of the test specimens. Keywords: all-ceramic, CAD/CAM, marginal discrepancy, marginal fit