A multivariate analysis using Cox's proportional hazards model was carried out on 73 patients with carcinoma of the lower alveolus and gingiva treated by surgery, to identify prognostic indicators for survival. Disease-specific survival was adversely affected by the type of mandibular absorption on X-ray (p=0.0055) and pathologically proven cervical lymph node metastasis (p=0.0277) . Disease-specific five-year cumulative survival rates according to the type of mandibular absorption were 93.5% for patients with no change, 92.9% for patients with erosive type, and 53.6% for patients with invasive type. Radiological findings of mandibular absorption can represent various characteristics and behaviors of carcinoma of the lower alveolus and gingiva. Disease-specific survival rates according to the cervical lymph node metastasis were 91.8% for patients without metastasis, and 54.1% for patients with metastasis. The invasive type of mandibular absorption on X-ray and pathologically proven lymph node metastasis was strongly associated with a poor prognosis for carcinoma of the lower alveolus and gingiva.