Glioblastomas are the most frequent malignant brain tumor in adults and are widespread in the brain despite their discrete appearance on CT or MRI. While locally aggressive, metastasis of glioblastoma to extracranial organs is considered rare. Approximately 10% of patients with glioblastoma develop metastatic disease after radiation or craniotomy. Few patients have developed extracranial metastatic disease in the absence of surgical resection or radiation. Unlike tumors of other organs such as lung, colon and prostate, the presence of glioma cells in the circulation of patients undergoing surgical resection has not been established. If found absent, glioma cells may be unable to intravasate through the blood brain barrier. If present, these tumor cells presumably can intravasate but may be recognized and eliminated by an immunological process, or they may escape detection yet not be able to take hold in the new microenvironment. The information provided will add to the knowledge of the biology of these highly malignant tumors.