Metastases of malignant tumors to the oral region from distant sites are uncommon. A 45-year-old man with painless gingival swelling was diagnosed with adenocarcinoma of the lung. On cytology, clusters of tumor cells on mucous background revealed enlarged nuclei, indistinct cell borders, and irregular nuclear membranes. Some cells showed nuclear inclusions, nuclear grooves and small nucleoli. These findings are indicative of metastatic adenocarcinoma. We present a case of gingival metastasis from a lung adenocarcinoma.