Introduction:Complete denture is used to replace the entire dentition and restore mastication, speech, and aesthetics. All other tooth-supported solutions have been exhausted. Because Computer-Aided Design/ Computer-Aided Manufacturing (CAD/ CAM) dentures are milled from pre-polymerized Polymethyl Methacrylate (PMMA) blocks that do not display polymerization shrinkage, they can eliminate the laboratory processes of acrylic processing (setting up of teeth, try-in, flasking and de flasking). Aim: to compare the retention values of maxillary conventional heat-polymerized denture bases with digitally milled denture bases. Materials and Methods: Sixteen totally edentulous patients participated in the study, which was divided into two groups (n=8) (A) and (B). Patients in the group (A) received traditional heat-cured acrylic resin dentures with a long cycle water path curing procedure, in group (B) received dentures created using the CAD/CAM technique. For both groups, a metallic hook affixed to the geometric center of the maxillary dentures was pulled by a digital force-meter gauge to measure retention. Results: The mean retention values were recorded for both groups, tabulated, and statistically analyzed; the following results were obtained. Regarding group (A), retention values showed a significant increase at the beginning of the study as well as at the end of the study. Regarding group (B), retention values showed a significant initial increase at the beginning of the study, till the end of the study. A significant difference was revealed between the mean retention values of the two tested groups, with clear superiority of the retention of the CAD/CAM acrylic resin dentures (group B) than that of the conventional heat-cured acrylic resin dentures (group A). Conclusion: CAD/CAM acrylic resin dentures were superior in terms of maxillary denture retention compared to conventional heat-cured acrylic resin dentures. Retention was increased gradually over time in both two studied groups.