Subpontic osseous hyperplasia is an ectopic growth of bone occurring on the edentulous ridge beneath a fixed partial denture replacing a mandibular first molar. A 56-year-old woman experienced an enlargement of the hard and soft tissues beneath the pontic region of a fixed partial denture replacing her mandibular left first molar. Following removal of the fixed partial denture, the bony enlargement was surgically removed, and the bony fragments were submitted for histologic analysis, which demonstrated mature lamellar bone and appositional growth. One year postoperatively, there has been no recurrence of the lesion. The possible etiologies and treatment modalities are reviewed and a rationale for treatment is presented.