Purpose: The purpose of this study was to evaluate prospectively the clinical effectiveness of immediate loading of implants with complete-arch fixed prostheses in edentulous maxillae after the implants were placed with flapless guided surgery. Materials and Methods: Patients with edentulous maxillae who visited a single dental clinic during the recruitment period (April 2011 to May 2012) were selected by consecutive sampling and predetermined selection criteria. Four to six implants were placed in each patient with flapless guided surgery. The outcome measures were insertion torque, surgical time, postoperative pain (100-mm visual analog scale), marginal bone level change, implant survival, and oral health-related quality of life. Patients were followed for up to 1 year. Results: Fifty patients received 290 implants. All implants were immediately loaded 2 hours after placement with prefabricated fixed provisional prostheses. Two patients dropped out of the study. Hence, analyses were conducted for 278 implants in 48 patients (26 men, 22 women; mean age 56.0 ± 8.3 years; age range, 34 to 74 years). The average insertion torque was 57.7 ± 16.6 Ncm, the average surgical time was 22.9 ± 4.7 minutes, and the average score for postoperative pain was 14.7 ± 9.3. One year after immediate loading, the implant survival rate was 98.6%. Four implants showed mobility early after implant placement and were lost. Mean marginal bone level changes were -0.32 ± 0.43 mm. Scores on the Oral Health Impact Profile-54 (Japanese version) improved significantly after prosthetic treatment. Conclusion: The results of this study indicate that this treatment method for edentulous maxillae is predictable, with a high implant survival rate and a clinically reasonable improvement in oral health-related quality of life. Keywords: alveolar bone loss, computer-aided surgery, dental implants, edentulous jaw, immediate dental loading implant, survival rate