This study investigated the dimensional change and microstructure of intraoral bone block grafts covered with platelet-rich fibrin (PRF) and a barrier membrane in ridge augmentation. Seven patients were included, with 18 implant sites (10 ramus and 8 symphysis). The average final ridge width gains in the ramus from cast-based measurement (3.86 ± 0.87 mm) and cone beam computed tomography measurements (3.63 ± 1.38 mm) were not different from the symphysis (3.36 ± 2.26 mm and 3.44 ± 1.52 mm, respectively). Ridge width reduction of the ramus (−10.46 ± 10.55%) was higher than the symphysis (−5.04 ± 2.08%). The ramus showed bone volume fractions from the microcomputed tomography (84.66 ± 8.36%) and percentage of bone area from histomorphometry (80.29 ± 12.03%) that were comparable to those for the symphysis (83.13 ± 8.1% and 84.98 ± 14.50%, respectively). The dimensional change of the intraoral block graft covered with PRF and a resorbable membrane was minimal, and the symphysis graft was less resorbed than the ramus graft. Nevertheless, their microstructures were comparable.