Purpose: The aim of this study was to investigate the effect of immediately loaded mini dental implants (MDIs) used to support mandibular overdentures on the peri-implant bone level as well as patients' related levels of satisfaction and quality of life. Materials and Methods: Four MDIs were placed in the interforaminal region of 10 completely edentulous patients, and the implants were loaded immediately (same day) with an overdenture. Radiographic assessment of the bone loss during a period of 18 months was performed by measuring the bone level changes at the mesial and distal aspects of each implant on panoramic radiographs. At the end of this period, patients' satisfaction level on the visual analog scale (VAS) and oral health-related quality of life was assessed by means of questionnaires. Results: A mean bone loss of 1.04 mm on the mesial and distal sides was recorded during the 18-month period after loading of the implants. The score for general satisfaction level was 95.67 ± 5.68. Similarly high VAS scores were given by the patients in all other specific items on patient satisfaction. The total score for the Oral Health Impact Profile-20 (OHIP-20) was 34.07 ± 13.90, which was comparable to that recorded in other studies. Conclusion: The short-term radiographic peri-implant bone level changes of MDIs immediately loaded with overdentures in the edentulous mandible were within the physiologic limits. The patients expressed a high level of satisfaction and oral health-related quality of life with this treatment modality. Keywords: immediate loading, mini dental implants, OHIP-20, radiographic bone loss, VAS