Multiple electroencephalography (EEG) abnormalities have been associated with autism. In the course of clinical work, we have observed a posterior dominant EEG rhythm at higher frequency in children with autism. To test this observation, 56 EEG tracings of children with autism were compared to the EEGs of age-matched controls. Children with autism showed a posterior dominant EEG rhythm (PDR) of 9.00Hz versus 8.60Hz for controls (p = 0.014). This difference was greater at younger ages. Neural correlates of an increased alpha frequency are unclear. This may represent pathology in cortical-thalamic circuits, default mode network, dorsal attention network and/or occipital visual networks. Examination of changes in these circuits in autism may be a worthwhile area for future research. (Contains 1 table and 1 figure.)