Objective: Resonance frequency analysis (RFA) has enabled the assessment of implant stability in terms of implant stability quotient (ISQ) units. This study evaluated the long-term stability of endosseous implants according to an ISQ scale of 1 to 100, as estimated by RFA in the posterior partially edentulous mandible. Method and Materials: A 2-stage procedure was used to place 328 Bränemark implants in the edentulous mandibular molar region (second premolar to second molar) of 113 patients (49 men and 64 women). Patients were followed at regular intervals postoperatively, and ISQ scores were evaluated by RFA every year for 10 years. Results: The implant success rate was 100%. ISQ scores did not significantly differ in the pattern of stability changes among different bone quantities and qualities during long-term follow-up. There was no significant difference in implant stability among the mandibular sides, the sites, and the sexes. Conclusion: Long-term stability of Bränemark implants was excellent in the posterior partially edentulous mandible. Keywords: dental implant, long-term clinical study, posterior partially edentulous mandible, resonance frequency, stability