Aim: to assess the implant stability and amount of crestal bone loss in immediate implant placement in mandibular molars by using pre-extractive inter-radicular implant bed preparation versus conventional post-extractive inter-radicular implant bed preparation. Subjects and Methods: Twenty patients (5 males, 15 females), suffering from badly decayed vital or non-vital posterior mandibular molar teeth were selected and randomly divided into 2 groups, 10 per group; the first group received Pre-extractive interradicular implant bed preparation while the second group received Conventional post-extractive interradicular implant bed preparation. Results: immediateImplant stability results that assessed using Osstell device measuring ISQ values between groups were (58±0.81 ISQ units) for the test group and (54.6±1.07 ISQ units) for the control group at immediate implant placement which represent significant differences (p<0.001). marginal bone loss results of mesial and distal bones between one-year and six-months' post-operative implant placement were (0.21 ±0.09 mm) in the test group and (0.37±0.17 mm) in the control group and marginal bone loss results of buccal and lingual bones between same periods were (0.21 ±0.04 mm) in the test group and (0.42±0.21 mm) of the control groups with significant differences of (p=0.022*) in mesial and distal bone loss and (p=0.006*) in buccal and lingual bone loss between groups. Conclusion: Implants that placed by pre-extractive inter-radicular implant bed preparation had a high primary stability and a less marginal bone loss in both bucco-lingual and mesio-distal dimensions from six-months to one-year than that placed by post-extractive inter-radicular implant bed preparation.