This study investigated the effect of bone grafting on hard and soft tissue alterations after immediate implant insertion in mandibular molar sites. This randomized, double-blind clinical trial consisted of 30 healthy patients (17 women and 13 men aged 22-58 years) who required immediate implant installation to replace a first or second mandibular molar. Only subjects with a buccal gap between 2 and 4 mm were selected. The participants were randomly allocated to two groups. In the experimental group, the gap was augmented by an allograft, whereas in the control group no graft was applied. Marginal bone level, probing depth, keratinized gingival width, and bleeding on probing were assessed at the time of implant placement (T0), 1 month (T1), and 3 months (T2) after surgery. There was no significant difference in hard and soft tissue parameters between the grafted and nongrafted sites at any of the durations (P < 0.05). Bone level decreased significantly in both groups (P < 0.05). However, the amount of probing depth and the frequency of cases showing bleeding on probing did not alter over the experiment either in the test or in the control group (P > 0.05). Bone grafting simultaneously with immediate implant installation had no significant effect on hard and soft tissue outcomes when the buccal gap size was between 2 and 4 mm. Therefore, the use of a bone substitute is not mandatory up to the jumping distance of 4 mm in immediate implant surgery.