At the department of prosthodontics, the elderly patients with severely atrophied alveolar ridge who have been wearing complete dentures for a long period frequently visit the clinic. In general, the open-mouth impression technique for manufacturing a mandibular complete denture to secure primary support on buccal shelf area has been prevalent. In addition, for securing retention and stability of mandibular denture, we should consider diagnosis, oral function, denture border, occlusal plane, teeth arrangement, and patient training, etc.. But in edentulous patients with severe alveolar bone atrophy, it may hardly secure retention and stability of mandibular complete denture. To promote these, some of clinicians are making an attempt manufacturing the mandibular complete dentures using closed-mouth impression technique based on several reports that compare various impression techniques including open-mouth and closed-mouth impression technique. This case report suggests closed-mouth impression technique may promote retention and stability of mandibular complete denture and compares between the two impression techniques clinically.