The authors studied the relationship between cerebral metabolism and brain electrical activity in patients with acquired immunodeficiency syndrome (AIDS), using positron-emission tomography and quantitative electroencephalography. Electroencephalographic coherence in the 6-to 10-Hz band correlated positively with thalamic metabolic activity. Coherence adjusted for background activity correlated strongly and positively with basal ganglia metabolic activity. Posterior interhemispheric coherence showed the highest correlations with measures of metabolic activity. These results suggest that changes in coherence may reflect AIDS-related subcortical disease. The high correlations between the two different measures of cerebral activity support the validity of electroencephalographic coherence measures in studies of AIDS-related neuropsychiatric dysfunction.