Purpose: Different graft materials have been proposed to minimize the reduction in ridge volume after tooth extraction. The aim of the present study was to compare the use of synthetic magnesium-enriched hydroxyapatite (MHA) with porcine bone (PB) grafts in fresh sockets by histologic and histomorphometric analyses. Materials and Methods: Forty-five fresh extraction sockets were selected in 15 patients. A split-mouth design was used: 15 sockets received MHA in one side of the jaw (MHA group), 15 sockets on the other side received PB (PB group), and 15 random unfilled sockets were considered the control group. Four months after surgery, cylindric bone specimens were harvested for histologic and histomorphometric analyses. Results: Histologic examinations revealed an absence of inflammatory cells, bone formation in all treated sites, and the presence of biomaterial particles and connective tissue. Mean vital bone measurements for the MHA, PB, and control groups were 36.5% ± 2.6%, 38.0% ± 16.2%, and 30.3% ± 4.8%, respectively. Statistically significant differences were found between the MHA and control groups and between the PB and control groups; differences between the MHA and PB groups were not significant. Connective tissue percentages averaged 33.3% ± 1.5% for the MHA group, 25.3% ± 9.4% for the PB group, and 58.3% ± 7.1% for the control group. Statistically significant differences were found between all groups. Residual graft material occupied 32.2% ± 3.2% of the MHA-grafted sites and 36.6% ± 4.8% of the PB sites. This difference was not statistically significant. Conclusions: Within the limits of this study, histologic examination showed the same biologic behavior in bone formation and resorption processes for the two examined biomaterials. Parole chiave: alveolar ridge preservation, hydroxyapatite, porcine bone, tooth extraction, wound healing