Purpose: To examine and compare the trueness between a computer-aided design (CAD) file and the final milled prosthesis. Materials and Methods: For each included patient (n = 30), two lithium disilicate crowns were produced (n = 60) using two different CAD/computer-assisted manufacture (CAD/CAM) systems (allin- one type and combination type). To compare the trueness, the scanned internal surfaces of the fabricated prostheses were compared to the design files in CAD using 3D analysis software (Geomagic Control X, 3D Systems). Results: The mean ± standard deviation root mean square value for posterior teeth was 32.2 ± 9.4 in the combination type group and 43.8 ± 11.7 in the all-in-one type group, indicating higher trueness for the combination type (P .05). Conclusion: This study has shown that the final milled prosthesis in combination type CAD/CAM systems had better trueness than the all-in-one system.