Sixty-three patients with malignant glioma undergoing chemotherapy and radiotherapy were evaluated with electroencephalography, 99mTc-DTPA imaging, and computed tomography (CT). Tumor size, central lucency, contrast enhancement, surrounding edema, and ventricular size were assessed. CT findings were found to be reliable and often predicted the clinical course. Tumor size, central lucency, and contrast enhancement increased in patients with clinical deterioration and decreased in those with improvement. The CT scan also provided additional information of value in adjunctive therapy, such as the presence of cysts or ventricular obstruction. In general, CT gave a more complete profile of tumor characteristics than other diagnostic modalities.