Abstract The clinical histories and findings at necropsy were reviewed in 100 consecutive patients with carcinoma of the lung, in 92 of whom the brain was included in the post-mortem examination. All patients were men (85 white and 15 Negro), and 76 per cent were in the sixth decade of life or older. Intracranial metastasis occurred in 30 of the 92 patients, that is, one in three. Metastasis to the brain was exceeded in frequency only by metastasis to regional lymph nodes, liver, and suprarenal glands, and occurred more often in the brain than in the skeleton, pancreas, and kidneys. The frequency of intracranial metastasis from carcinoma of the lung bore no relationship to the cell type. Among the 30 patients with intracranial metastasis, 10 had clinical manifestations of central nervous system involvement as the presenting complaint, 9 had neurological symptoms for six weeks or less prior to death, and 11 had no symptoms indicative of central nervous system involvement.