This study was conducted to compare the effect of two different denture base materials (rapid heat cure acrylic resin and modified rapid heat cure acrylic resin with titanium dioxide nanoparticles) on the retention of maxillary complete denture.The study was carried out on twelve patients with completely edentulous maxilla that they were randomly selected from the eligible patients who met the following the inclusion and exclusion criteria. Standard dentures were constructed. Each patient received two dentures, after duplication of the master casts using duplicating silicone mold. One made of rapid heat cure acrylic denture base (vertex rapid simplified) and the other was made of modified rapid heat cure acrylic denture base (vertex rapid simplified) with titanium dioxide nanoparticles.Geometrical center was determined using the intersection of two lines; one extending from incisive papilla to fovea palatinae and the other extending from the premolar area of one side to the premolar area of the other side.A ready-made metallic hook was screwed to a metallic hexagonal nut which was attached to the polished surface of the maxillary denture using self-cure acrylic resin at the geometrical center.Digital force-gauge was attached to the ready-made metallic hook to apply force while the patient’s head was in upright position where the maxillary occlusal plane parallel to the floor.Measurements were recorded twice for each denture; 1st time immediately after delivery. 2nd time after 1 month to get maximum tissue adaptation for better retention results.Wash out period was applied for 1 week between the two types of dentures to eliminate the carry-on effect.From this study, it could be concluded that:1. Retention had increased by time in each study group.2. Retention of the modified rapid heat cure acrylic resin with titanium dioxide nanoparticles was superior to that of the rapid heat cure acrylic resin.3. Retention of the complete dentures could be enhanced by adding titanium dioxide nanoparticles.