Fourteen patients who had cognitive dysfunction were studied with quantitative electroencephalography (EEG), singlephoton emission computed tomography (SPECT), and several tests of intellectual and memory function, including the Wechsler Adult Intelligence Scale (WAIS), the Auditory Verbal Learning Test, and the Short Test of Mental Status, to determine whether EEG background frequency content correlates with degree of dementia and with regional uptake of radioisotope on SPECT. The factors from spectral analysis that correlated best with psychometric data were mean frequency in the 1.5– to 20-Hz range and percentage power in the 13- to 20-Hz band (positive correlation) or the 1.5- to 8-Hz band (negative correlation). The WAIS subtest scores that correlated most with the EEG data were performance IQ and perceptual organization. Correlations between percentage power and amplitude ratio in the EEG frequency bands and regional SPECT counts were found, but most were not statistically significant. ( J Geriatr Psychiatry Neurol 1992;5:22–30).