The aim of this retrospective study was to evaluate the alveolar dimensions of the mandibular molar using cone beam computed tomography (CBCT) for immediate implant placement. The width of buccal (WB) and lingual (WL) bone; width of interradicular bone 2 and 4 mm apical to the furcation and at the apex (IRB2, IRB4, and IRBA, respectively); and distance to the inferior alveolar nerve from the furcation (IAN-F) and mesial (IAN-M) and distal (IAN-D) roots were evaluated from CBCT records of 126 subjects (200 mandibular first molars). Mean WB (0.84 ± 0.39 mm) and WL (2.71 ± 1.17 mm) measurements showed significant differences (P = .003). Differences between IAN-F, IAN-M, and IAN-D measurements averaged at 14.14 ± 2.57 mm, 4.31 ± 1.06 mm, and 4.61 ± 1.02 mm, respectively. IRB2, IRB4, and IRBA dimensions were 1.93 ± 0.65 mm, 2.54 ± 0.9 mm, and 4.46 ± 1.91 mm, respectively. The findings of the study demonstrate the alveolar bone morphology of the mandibular first molar and the need for CBCT scans for proper treatment planning for immediate implant placement.