Intradural spinal metastases can develop following dissemination via the cerebrospinal fluid from various primary or secondary brain tumors. Since the risk of intradural spinal metastases has never been formally studied in patients with brain metastases, we reviewed patients with brain metastases from bronchogenic carcinomas and looked for the subsequent development of intradural spinal metastases. Of 160 consecutive patients, only 6 presented intradural spinal metastases, however none were among the 105 patients who had exclusively supratentorial metastases and all intradural spinal metastases were in patients who had lesions in the posterior fossa. In this group, the 1-year actuarial risk of having intradural spinal metastases was 21% (p less than .01 compared with patients who had supratentorial metastases). We could not find any other risk factor for intradural spinal metastases. Recommendations for the group of patients with increased risk of intradural spinal metastases are made.