IN A RETROSPECTIVE study of 82 cases of oligodendroglioma, the influences of tumor size, site, and grade, the age of the patient, the extent of surgical excision, and the effect of additional radiation therapy on the clinical course, as well as their dependencies, were investigated. Tumor grade and tumor site significantly affected the survival rates of the patients. When tumor site was kept constant by distinguishing between frontal and nonfrontal localized oligodendrogliomas, the grading system still showed discriminating power. Conversely, when controlled for grade, the frontal site appeared to be favorable for prognosis. Age was only faintly correlated with survival, with younger patients tending to survive longer. This was compatible with the finding that, in younger patients, more frontal localized tumors were found and that older patients had oligodendrogliomas with higher grades. Tumor volumes did not correlate with survival. No correlation between tumor volume and tumor grade was found. Patients who had undergone a decompression tended toward longer survival, although this trend did not reach significance. No beneficial effect of radiation therapy on the survival rate was demonstrable.