Intracranial meningiomas were detected in 164 of the 2,928 patients in the National Cancer Institute study of computed tomography (CT) in the diagnosis of intracranial tumors. The comparative effectiveness of contrast-enhanced and noncontrast CT scanning and other radiological modalities--plain skull radiography, angiography, radionuclide studies, and pneumoencephalography--was assessed. CT was demonstrated to be the most accurate method for detecting intracranial meningiomas (accuracy of 84.8% for noncontrast and 96.2% for contrast-enhanced CT). It was significantly more accurate than radionuclide studies and plain radiography, and was slightly more accurate than angiography. Pneumoencephalography was performed in only five cases, and identified a mass in four. Angiography was useful for increasing the percentage of specific diagnoses.