Purpose: The aim of this study was to evaluate the effect of different digital impression techniques (two direct digitizing systems and one indirect digitizing system) on vertical marginal adaptation of a CAD/CAM zirconia coping. Materials and Methods: One intact, non-carious human maxillary first premolar was selected for this study. A standard preparation for the tooth was done to receive a full coverage single zirconia coping. The tooth was adjusted in a model representing the dental arch (master model). The samples were divided into three groups: Group A consisted of 7 direct master model scans with the Cerec omnicam, Group B consisted of 7 direct master model scans with the Cerec bluecam, Group C consisted of 7indirect scans of the conventional impression with the Cerec inEosx5. In all groups the copings designed with same software same milled block material and same milling machine. Marginal fit was evaluated by the measurement of vertical marginal adaptation by the aid of digital-microscope, magnification X 50, and the images were captured and transferred to an IBM personal computer equipped with the Image-tool software. Results: Regardless to measured surface totally it was found that, group C recorded highest vertical marginal gap (24.76 ± 5.9 µm) followed by group B which recorded mean±SD of (24.56 ± 4.5 µm) while the lowest vetical marginal gap (21.47 ± 4.8 µm) was recorded by group A. The difference of vetical marginal gap between all technique groups was statistically significant (p<0.05) as indicated by ANOVA test. Also it was found that, Indirect conventional impression digitizing recorded higher vetical marginal gap (24.76±5.9 µm) than Direct model digitizing which recorded mean±SD of (23.02±3.4 µm). The difference of gap between both techniques was statistically non-significant. While Regarding to the effect of measured surfaces it was found that, distal surface recorded highest vetical marginal gap (25.65 ± 6.2 µm) followed by buccal surface which recorded mean±SD of (24.26 ± 4.9 µm) then mesial surface which recorded mean±SD of (23.61 ± 3.5 µm) while the lowest vetical marginal gap (20.87 ± 5.4 µm) was recorded at lingual surface. The difference of vetical marginal gap between all technique groups was statistically significant (p<0.05) as indicated by ANOVA test. Conclusions: 1. All marginal adaptation values recorded in the tested groups are not only clinically acceptanced but more adapted than the range of clinically accepted values. 2. Digitizing techniques ( CEREC Omnicam , CEREC Bluecam, CEREC inEos X5 ) had influence on the marginal adaptation of zirconia copings. 3. CEREC Omnicam is the most appropriate digitizing technique in obtaining the best marginal adaptation. 4. Marginal gap values are affected by the location of the measurements. (The values for palatal and mesial surface were lower than those on buccal and distal ones).