Purpose: This case series evaluated the implant success rate and peri-implant tissue response of immediately loaded unsplinted implants retaining a mandibular overdenture. Materials and Methods: Eight completely edentulous patients (five men, three women) with a mean age of 69.1 years were included in the study. All participants received new maxillary and mandibular complete dentures prior to implant placement. Two 4.0- 3 13-mm threaded implants with a fluoride-modified microrough titanium surface were placed mesial to the mandibular canine position bilaterally. Individual stud attachments were connected and torqued to 25 Ncm and the overdenture was immediately attached. The patients were evaluated clinically and radiographically at implant placement and at 3, 6, and 12 months after implant placement. The data were analyzed using the paired-samples t test and the Wilcoxon signed-ranks test at a significance level of a = .05. Results: At 12 months, all implants remained osseointegrated and showed an overall mean marginal bone change of -0.36 ± 0.29 mm and a mean Periotest value of -6.94 ± 0.73. The modified Plaque Index scores indicated improvements in oral hygiene over time. Surgical complications involved two episodes of implant rotational instability. Prosthetic complications were attributed to abutment loosening, the patients' inability to insert the prosthesis correctly, and soft tissue shrinkage. Conclusions: The results of this study suggest that favorable implant success rates and peri-implant tissue responses can be achieved with mandibular overdentures retained with two immediately loaded unsplinted threaded implants with a fluoride-modified microrough titanium surface. Keywords: immediate loading, implant-retained prosthesis, locator abutment, mandibular overdenture, unsplinted