Objective: The aim of this present study was to evaluate the relation between primary implant stability of delayed implant placement and bone density in posterior mandibular area.Patients and methods: 16 implants were placed for 9 patients (6 females and 3 males) that had at least a missing one mandibular posterior tooth. Bone density of each implant site was measured preoperatively through orthopantomograph. The implant osteotomy was done according to the manufacture’s instruction under copious irrigation after the replacement of the pilot drill with a 2.0mm trephine bur to obtain a core biopsy with a fixed starting torque of 15Nm2. For each implant primary implant stability was measured immediately postoperatively by resonance frequency analysis.Results: For all the 16 implants sites, bone density was D4. All the 16 implants were stable with a mean primary stability of 69.9(+\- 14.5) ISQ.Conclusion: There is no correlation between primary implant stability and bone density and drilling torque.