Five percent of all malignancies involve the oral cavity, only 1 % of these malignancies are metastatic from neoplasms. There are more published cases of jaw bone metastases than in oral soft tissue. The most common primary sources of metastatic tumors to the oral region are the breast 、lung 、kidney 、bone and colon. The breast is the most common primary site for tumors metastasizing to the jaw bones, where the lung is the most common source for metastases to the oral soft tissue. In the jaw bones, the common location of the metastatic lesions is the mandible, with the molar area being the most frequent involved site. In the oral soft tissues, the attached gingival is the most common affected site followed by the tongue. In nearly 30% of cases, the metastatic lesion in the oral region is the first indication of an undiscovered malignancy at a distant site. A case of metastatic adenocystic carcinoma of the lung involving the area of a recently extracted mandibular second premolar is reported.